The residents of Washington DC gather round as the church bell summons them for an important announcement. Usually, the bell is a signal of disaster, but this morning - Good Friday, April 14th 1865 - the news is of a rebellion ended and of the end of the war. Most of the crowd cheers, but among them are some hecklers, unhappy that blood was spilt by their fathers, brothers and sons for nothing except to keep them in the poor house and give the slaves a vote. One heckler in particular begins to shout “no surrender”, but he finds himself being booed by the others and eventually he’s escorted away on the orders of Officer John Parker and given very rough treatment.

Parker’s actions are mocked by another man, the theatre actor John Wilkes Booth, who is evidently still the worse for wear from drinking the previous night and can only stand up with the help of a nearby lamp post. The officer is also criticised by Clara Harris, who rebukes him for allowing rowdies to run amok on the streets. Parker suggests that anyone shooting their mouth off on a day when feelings are running so high deserve a little roughing, but when Clara protests further, he agrees to go and talk some sense into the men. Once Parker has gone, Booth says it would be a pleasure if Clara would allow him to escort her to a less troublesome spot, but she tells him that every woman in Washington knows of his ’pleasure’ and says she’ll be perfectly safe without his protection. Clara returns to the crowd as they’re urged to banish any feelings they may have of revenge…

In Ford’s Theatre, Henry Clay Ford rebukes one of his staff, a young man named Pops, for not waiting by the stage door as ordered. They’re expecting the arrival of a special guest from England, Mr Oscar Wilde, but Pops is nowhere to be seen. When Ford investigates a strange smell coming from the dressing room, he’s surprised to find it’s already occupied. Ford introduces himself and comments on the overpowering scent, which Wilde explains is the result of an infusion of lavender and bergamot that he uses to soothe his nerves. Ford welcomes him to the theatre and asks how he got in here and Wilde says he was let in by the boy Pops. Ford is delighted and predicts that Oscar Wilde’s famous wit is going to make him famous across the whole United States. Ford says he read the script of Wilde’s new play “The Importance of Being Earnest” as soon as it arrived and by the end he was literally laughing his head off. Wilde says he’s tired and asks if he could be left alone. Ford realises Wilde must have had a long journey, but he has no idea how right he is…

Inside the TARDIS, the Doctor is repairing the instruments underneath the stalled console with a hammer while confusing Evelyn with references to Percy George Herbert Fender who he says was the finest cricketer ever to captain England and was one of the true gentlemen of the game. It’s reminded the Doctor that experience and knowledge is what really counts and, like Fender, each strike has to be precisely timed and weighted. He promptly thumps the console and the rotor begins functioning normally again. The TARDIS lands and the Doctor announces they’re on Earth again. The year is 1865, which Evelyn recalls is noted for many famous events, so the Doctor decides they should go outside and take a look around.

Booth returns to the theatre box office to see if there are any messages for him. Ford says he’s always pleased to see distinguished members of the local company, but this is a sore point for Booth who’s feeling under threat from a new and even more distinguished member, Harry Hawk. There’s a letter waiting for Booth which he starts to read, but before he finishes he’s distracted by Ford’s casual mention that General Grant will be visiting the theatre tonight with none other than President Abraham Lincoln. The letter for Booth was from Oscar Wilde, inviting him to audition. Ford confirms that he’s in collaboration with Wilde so Booth decides to visit him. When Ford returns to the manager’s office, he’s shocked to find the Doctor and Evelyn inside, together with a huge blue box. The Doctor offers Evelyn the chance to provide the explanation for their presence, but for once she’s lost for words.

Booth arrives at the dressing room and immediately comments on the unusual atmosphere inside, which the elderly Englishman says is lavender and bergamot. Booth has noticed a large cabinet which Wilde says contains his curiosities. Booth seems nervous and Wilde acknowledges that in these times a man with such sympathies needs to be careful. Booth becomes angry and holds a knife to Wilde’s throat, demanding to know what he meant by that remark, but Wilde says he was simply referring to those ’platonic sympathies’ that are common to all actors but are tragically misunderstood in the wider world. Booth relaxes and assures Wilde that he only has eyes for the ladies. Wilde offers his visitor a glass of elderberry cordial and promises that it’s full of anti-oxidants. He tells Booth he saw him last year in Boston appearing in a Shakespeare play and concluded that he was watching the finest actor on the American stage. He says Booth could rival any performer from England, including Edmund Kean and even Laurence Olivier - and when Booth says he’s never heard of the latter, Wilde realises he’s getting ahead of himself. In any case, he’s written a piece especially for Booth in which he‘s to play a hero called Jack who thinks himself to be Ernest…

Ford accuses the Doctor and Evelyn of being burglars and says he’s already banked last night’s takings. The Doctor knows he’s lying and points to the pile of money on the desk, but assures Ford he has no interest in the takings. Ford recognises the Doctor’s accent as English and assumes they’re theatricals who’ve come here with Oscar Wilde, although he thinks the Doctor is even more of a dandy than Wilde is. The Doctor stops in his tracks and realises something odd is going on - the year is 1865, which means Oscar Wilde wouldn’t be out of short trousers yet. When they discover they’re in Ford’s Theatre in Washington DC on the very day Abraham Lincoln will be assassinated, the Doctor demands to see Oscar Wilde immediately.

At the White House, Major Thomas Eckert opens the door to the famous Blue Room and allows Lizzie Williams to take a quick peek. She goes inside and tells him to shut the door if he doesn’t want to get into trouble. Eckert is nervous as anyone could catch them - even the President himself - but Lizzie thinks he enjoys the danger and excitement. She asks Eckert to take her out tonight and when he says he’s working, she suggests he call in sick. As they kiss, the door opens and a horrified Clara Harris walks in on them. She says she can’t believe her eyes and demands to know who the strange woman is, but when Lizzie speaks back to her, Clara tells Eckert he’ll have to explain his behaviour to the President.

Ford proudly tells the Doctor and Evelyn that Oscar Wilde will also be performing at the theatre and asks if it’s true that his Prospero was praised by none other than Queen Victoria and that his Bottom is a marvel to behold? Evelyn asks the Doctor if it’s likely the man they’re about to meet could be the real Oscar Wilde, but the Doctor says there was no mention of him being a time traveller in the programme notes when he went to see “The Importance of Being Earnest” thirty years from now. Evelyn jokes about him travelling around in a handbag, but the Doctor isn‘t in the mood for laughing. Given that they know Abraham Lincoln will be assassinated here later tonight, they need to find out what’s going on. They arrive at Wilde’s dressing room and although they find it empty, they’re immediately overcome by the awful smell. The Doctor is intrigued by Wilde’s strange cabinet which reminds him of the Chinese conjuror Chung Ling Soo’s magic box which he saw on the night when Ling Soo died during his bullet catching act at the Wood Green Empire in 1918. The Doctor is more determined than ever to find the man claiming to be Oscar Wilde and Ford tells him Johnny Booth was coming here to audition for him. Evelyn realises this must be John Wilkes Booth and the Doctor says things are getting very bad. Evelyn thinks it’s time they told Ford who they really are and she says the words ”we never sleep”. Ford instantly concludes that they’re Pinkerton agents and tells them Wilde and Booth are probably on the stage, so the Doctor races off alone. Ford notices that Wilde has left two glasses on the table and he tells Evelyn he fancies a drink.

Clara rebukes Major Eckert and says he’s abused the position of trust he holds at the White House. Lizzie intervenes and says he did no harm in showing her around, but Clara orders Eckert to remove her. Lizzie insists that she has just as much right to be here, but Clara points out that she’s the daughter of a Senator whereas Lizzie is clearly the daughter of the gutter. Lizzie storms out after reminding Eckert that he agreed to meet her later. Once they’re alone, Eckert pleads with Clara to show leniency and says this was just a moment of madness, but Clara has heard enough madness already today and she even heard people calling for the President’s blood during the rally this morning. Eckert assures her the President is safe and is surrounded by good men, but Clara isn’t sure she can trust the police any more. She tells Eckert he’s lost her trust and it’ll take a lot for him to get it back.

On the stage at Ford’s Theatre, Oscar Wilde listens as John Wilkes Booth reads lines from the play “The Importance of Being Earnest”. His performance isn’t to Wilde’s taste, so Booth does it again with a very poor imitation of an English accent. Suddenly they’re interrupted by the arrival of the Doctor and Wilde asks Booth to leave them alone for a few minutes. He is, in fact, is none other than the time travelling meddler who the Doctor and Evelyn encountered in Edinburgh when he was posing as Dr Robert Knox. Knox admits that he grew rather attached to that name and plans to continue using it. He tells the Doctor his business is flourishing and there’s fantastic money to be made out of legitimate theatre, particularly when the whole of Earth’s future is his to plunder, but the Doctor accuses him of being a temporal plagiarist. Booth calls out from the wings and tells ‘Wilde’ to get on with it, which makes the Doctor call back and ask what else Booth has planned for the rest of the day? Booth doesn’t care for the Doctor’s tone and Knox warns him to be careful as Booth is known to be a man of passion.

The Doctor accuses Knox of murder, but he denies it and suggests the poison may have actually been intended for him and left by a jealous theatrical rival who’d heard about his arrival. He insists he has nothing to hide and tells Ford to call the police. Ford is reluctant and reminds them the President is coming here tonight and says they can’t afford to get involved in a scandal. He promises to tell the police tomorrow and asks for help hiding the body until then. Knox declines, claiming he has a bad back due to a war wound he suffered during the Charge of the Light Brigade after his bayonet snagged in his new cardigan and he fell off his horse. Ford calls out for the boy Pops, but there’s still no response. With Booth dead, time’s equilibrium is now irretrievably upset, but Evelyn is curious to know what Knox will gain from Lincoln’s survival. Knox argues that Lincoln is a lovely, articulate chap and once his term of office is over, he has great plans for him, including lecture tours all over Europe and the East. The Doctor says that even though Booth is dead, it doesn’t mean Lincoln will be safe. Time abhors this sort of thing and right now it’ll be working silently to repair the damage Knox has done. Evelyn knows Lincoln doesn’t deserve to die, but if he lives then the consequences for American civil rights will be catastrophic. The Doctor points out that Booth isn’t the only person who hates Lincoln enough to kill him. Evelyn thinks Ford might be right to hide Booth’s body as the fewer witnesses there are, the less likely it is that history will be disrupted, but the Doctor says the moment they start covering up dead bodies, they might as well go into partnership with Knox. His mind is made up and he’s going to call Knox’s bluff by finding a policeman…

In a nearby gin joint, Lizzie Williams tells John Parker about her encounter with Clara Harris in the White House. Parker is indulging in some heavy drinking and Lizzie tells him that if a police officer needs that much “medicine” then he shouldn’t be on duty. He asks if her arrangements with Major Eckert are still set for tonight and she confirms they are. He asks her to buy him another drink, but when she tells him she’s out of money he tells her there’ll be plenty coming from the Major once they start blackmailing him for desertion and degeneracy. Suddenly Evelyn races in and calls out for a policeman. Parker reluctantly responds and Evelyn tells him there’s been a murder at Ford’s Theatre.

At the White House, Major Eckert drafts a letter to his manager explaining that he’s been taken ill and has handed over his duties for tonight to someone else. He struggles to make the wording sound convincing and is frustrated at himself for what he’s prepared to do to keep his girlfriend Lizzie happy.

The Doctor goes onto the street and bellows at the top of his voice that there’s been a murder, but everybody ignores him and passes by. Evelyn returns and says the people think he’s just promoting a new production at the theatre. She has Officer Parker with her, but from the way he’s swaying from side to side, it’s evident he’s had too much to drink. Parker threatens to lock them up for a week if this turns out to be nothing more than a stage-door hustle. They tell him John Wilkes Booth has been murdered and Parker starts to laugh. He knows Booth well and is convinced the scoundrel has put them up to this as a joke. The Doctor assures him his friend is stone dead, so Parker agrees to go with them.

Knox and Ford are unable to find Pops and Knox makes a flippant remark that he may have poisoned the boy too. Ford thinks the Doctor must be crazy to suggest that a gentleman as refined and delicate as Oscar Wilde could be a murderer. Knox stumbles and tells Ford offers it’s just an effect of his condition and Ford hastily suggests he returns to his dressing room to get some rest. They hear a voice shouting from the direction of the stage, so Ford tells Knox to wait here while he goes to investigate.

Parker is devastated when he finds the dead body of John Booth, but when Evelyn offers her sympathy she discovers his main concern is that he’ll never get back the money Booth owed him. It was only last night that he won 50 dollars from Booth in a game of poker and nobody will settle the debt now. The Doctor stresses that the suddenness of Booth’s death and the condition of his body points to murder, but Ford arrives on the stage and says it was nothing more than an unfortunate accident. He suggests that Booth had been burning the candle at both ends for years and it’s most likely that his heart simply gave up. Parker tells him to cover up the body, but Ford has a better idea and activates the trap door on the stage. The body disappears through the hole and Ford assures them he won’t be disturbed down there. Evelyn reminds them of the poison in the elderberry cordial and Ford explains to Parker that the strangers are actually agents for Pinkertons. The Doctor and Evelyn correct Ford’s misunderstanding and announce that they’re freelance, which Parker assumes makes them bounty hunters. They try to explain that Oscar Wilde is really Dr Knox, although that isn’t his real name either, but things start to get very complicated and Parker’s patience is running out. When Ford tells them he left Wilde outside his dressing room, they realise he’ll have ample opportunity to get rid of the evidence and get access to his TARDIS. As the Doctor and Evelyn race off, Ford invites Parker back to his office to discuss everything that’s happened.

Knox enters his TARDIS and asks his ship to activate the scanner. A calm female voice responds and Knox watches on the screen as the Doctor barges his way through the locked door, only to find the room empty. They examine his magical cabinet and the Doctor calls out for Knox to open up and show himself. Knox sighs and decides to face his nemesis. He opens the TARDIS door and allows the Doctor and Evelyn to enter…

Inside the ship, the Doctor is amazed to see that Knox has voice control over his TARDIS and he’s even installed a lift. Knox is delighted to announce that he’s traded up and now has all the mod cons. Evelyn is confused and wonders why Knox didn’t take the opportunity to escape. The Doctor assumes Knox’s TARDIS is broken, but when they check operational status he’s surprised to hear everything is working perfectly. Knox offers to show them the real reason why he’s still here, but the Doctor refuses to let him operate any controls as he’s sure they’ll just be lured into a cross-dimensional trap. Knox assures him he was only planning to take them a few blocks north-west to save his aged legs. He allows the Doctor to pilot the ship himself and the Doctor asks the ship for manual control. He begins plotting a small spatial displacement, but it soon becomes clear he‘s not familiar with operating such an advanced version of the TARDIS and Knox has to step in to assist him.

Parker joins Ford in his office and they sit down for a cigar. Parker suggests he should take more care about leaving his office unlocked, especially with his moneybox left open, ready for the taking. Ford admits that if the President gets wind of everything that’s happened here today, the chances are he’d cancel and go to a rival theatre instead. Parker will have to account for his own presence here and suggests Ford should claim the theatre was robbed and the previous night’s takings stolen. Then if the robbers broke in again, he’d have to come back tomorrow, whereupon he could find Booth’s dead body. It would be obvious the robbers had been disturbed and killed Booth during their escape. Ford agrees and allows Parker to help himself to all the money from the box. Then Parker leaves, promising to return the next morning.

Knox’s TARDIS materialises in a park and the chameleon circuit takes on the form of a bush to fit in with its environment. The Doctor queries why it chose earlier to disguise itself as Chung Ling Soo’s magical cabinet, but Knox ignores the question except to confirm that its appearance was accurate down to the last bullet hole. He tells them this is Lafayette Park and they head off in the direction of the White House. Evelyn wonders why they’re humouring Knox, but the Doctor doesn’t see that they have any choice. Booth may already be dead, but the effect on history won’t be noticed for another ten hours or so and until then, time is in flux. Things can still be changed, but first they have to know what Knox is up to. The Doctor doesn’t believe Knox’s claim to have plans for Lincoln and thinks there’s something much bigger going on. They catch up with Knox and find he’s arranged to meet someone here. Moments later they see a woman riding towards them and Knox describes her as an “angel of mercy”. Clara Harris dismounts and tells ’Mr Wilde’ what a pleasure it is to see him again. She apologises for being detained on government business. The group helps Clara unload some sacks from the horse and she explains that it’s food for the wildlife in the park, taken from the scraps left over every day from the lunches at the White House. After feeding the animals, Clara leaves and Knox agrees to meet here again at the same time tomorrow. After she’s gone, Evelyn tells the Doctor that Clara Harris is a Senator’s daughter and she’ll be chief witness to the assassination of Abraham Lincoln that was meant to take place later tonight.

Knox explains that it was during the assassination that he first saw Clara. He’s already attended Ford’s Theatre later tonight and he watched as Booth stepped into the box and fired directly into Lincoln’s head. Clara was there as a guest of the Lincolns with her fiancé, Major Rathbone. They were both last minute replacements for General Grant and his wife, and were mere inches from the President when he was killed. The Major reacted instantly and tried to remonstrate with Booth, but the assassin stabbed him several times with a Bowie knife, then he fleed the theatre as Clara screamed to the audience to stop him. What was supposed to be the greatest night of Clara’s life had instantly turned into the worst.

Evelyn picks up the story. Major Rathbone recovered from his injuries, at least physically, but the night’s madness never left him. Twenty years or so in the future, he will shoot Clara, then stab her to death. Evelyn finds the story too awful to tell, but Knox carries on. He dismisses Lincoln as just another “here today, gone tomorrow” politician whose usefulness was already behind him, but the real tragedy in this story is Clara. Hardly anybody weeps for her, even though her life will end tonight just as surely as Lincoln’s. The Doctor asks Knox outright whether he’s in love with Clara Harris, but Knox avoids answering the question and says it’s time to leave.

Evelyn refuses to believe a creature like Knox is capable of being in love with Clara, but the Doctor says he wouldn’t be the first man to lose his head over a pretty girl. Despite Evelyn saying Knox is probably older than Methuselah, the Doctor thinks he’s having the time meddler’s equivalent of a mid-life crisis. Evelyn says Knox’s ‘love-struck teenager’ routine stinks, very much like Knox himself and not just because of the lavender and bergamot. She asks if the Doctor’s noticed that underneath the overpowering scent, Knox absolutely reeks and his breath is like a labrador with halitosis. The Doctor doesn’t believe Knox’s declaration of love either and says if all he wants to do is save Clara, he didn’t have to actually kill Booth, just make sure she didn’t receive the invitation to join the Lincolns at the theatre. This gives Evelyn an idea and she asks why they don’t stop the messenger. The Doctor refuses to fiddle with the timeline any further, but Evelyn argues that if Knox has already altered history, then they can too. She suspects Major Rathbone is shortly due to meet a premature demise at Knox’s hands, and then Knox will move in to offer Clara his sympathy. While they’re busy arguing, Knox is becoming increasingly frustrated waiting for them at the TARDIS doors. Eventually he gives up and the ship promptly dematerialises, leaving the Doctor and Evelyn behind. Evelyn is angry with the Doctor for refusing to save Clara from a lifetime in Knox’s clutches, but the Doctor says there’s more at stake here than one woman’s happiness. They begin to argue and the Doctor upsets Evelyn with some clumsy words, so she storms off on her own, promising to see him back at the theatre later.

Dr Knox engages his TARDIS’s Fast Return switch, then he tells his ship he believes his work in 1865 is done as the Doctor seems to be taking care of business now. The ship changes course and Knox is disappointed that he won’t be around to see the surprises in store for his nemesis - then suddenly he starts to cough violently and finds blood on his handkerchief. The voice of the TARDIS recommends his immediate transfer to the sickbay, but Knox refuses and steps into the lift and heads for floor Gamma 7 instead. The ship asks Knox if he’d like to hear some music and it starts to play the “Can Can”, which he finds very jolly.

Major Eckert arrives at Lizzie’s room as she requested, but as he enters he’s shocked to find himself facing Officer John Parker, who has a gun pointing directly at him. Parker starts reading out sections from the love letters Eckert has sent Lizzie over the last few months. He says Eckert’s behaviour has been indecent, especially given his rank and the fact that he‘s a married man. Eckert is furious with Lizzie and says he would have given her money willingly if she’d asked for it. Parker says that although he can’t ignore gossip concerning the President’s chief protector, he has no desire to ruin a man’s career and destroy his reputation just for straying from the path. Then he tells Eckert that in his role as a police officer, he’s heard of some English aliens hiding out at Ford’s Theatre right now who he believes were smuggled in. They’re pretending to be actors but he believes they’re really seditionists and counter-revolutionaries, come to destroy Lincoln’s peace efforts. He tells Eckert that President Lincoln will be at the theatre tonight and lets the Major work out the rest. He says he can’t arrest or detain the new arrivals without evidence, so he needs someone to remove them - perhaps a soldier with an alibi, such as one who’s already told his boss he’s been taken ill. Eckert realises what’s being asked of him and Parker says he’ll hold onto the love letters for now, just to be on the safe side.

Knox arrives on floor Gamma 7 and orders his ship to ‘can’ the “Can Can” as the music doesn’t suit the ambience. He checks the equipment and reassures himself that the cage is secure and the beast inside is still contained, so why is he still decaying? He demands an answer from the creature, but when he gets no response he decides to prompt it with a couple of thousand volts. The creature howls in agony, then it explains that Knox himself has been contaminated and as a result, the link has been broken…

Evelyn arrives at the Harris home and finds Clara tending to her horses in the stables. Clara remembers her from when they met earlier in Lafayette Park and Evelyn says she’s come here to talk about ‘Mr Wilde’. She asks Clara if she’s known him long, but Clara virtually dismisses him as a strange old man and says she’s cast him a smile once or twice as a minor act of charity. Evelyn asks her to stop doing that and says she’s come here to warn her that Wilde has “designs” on her. Clara insists the feelings are not reciprocated and says she regards the old man as nothing more than a stinking itinerant. She says theatricals are all the same - degenerate, filthy-minded libertines - including John Wilkes Booth who she met just half an hour ago when he and Wilde ran out in front of her on Pennsylvania Avenue. Evelyn says she must be mistaken, but Clara insists that Booth even had the nerve to tip his hat at her and wink. Evelyn leaves, greatly concerned that Booth is still alive after all…

Major Eckert visits Ford’s Theatre and finds Henry Ford struggling vainly to drag a box from the stage. Ford explains that his stagehand Pops isn’t around, so Eckert offers to help him lift the box. He jokes that it’s heavy enough to have a dead body inside, but Ford tells him it contains various props. Eckert suggests they empty the box first, but Ford quickly intervenes and says they should leave it where it is until Pops returns. Eckert says he’s come to review the arrangements for the President’s visit. He asks for a list of everyone working here and he adds that he has a question or two about three individuals from England. Ford claims not to know who he means, but then the Doctor suddenly reappears and tells Eckert there’s a scoundrel backstage named Knox. When Ford says Knox has gone and taken his cabinet with him, the Doctor is concerned as he should have returned an hour ago. Eckert pulls a gun on the Doctor and arrests him on a charge of being a seditionist.

Lizzie returns to Parker with the things he asked her to collect. Using horsehair and gum she’s going to make him a false moustache and she has an opera cape and hat to complete the disguise. Tonight at Ford’s Theatre, Parker will complete the job John Booth was meant to undertake, and then shortly afterwards he will emerge dragging Booth’s corpse behind him. He’ll be America’s hero - the man who chased and killed President Lincoln’s assassin. Booth’s own letters will incriminate him and with any luck, Parker hopes to be promoted. Eventually he and Lizzie will be able to retire to their own plantation in the South and they’ll be set up for life. Lizzie reminds him that Ford knows Booth is already dead, but Parker is sure he won’t say anything to avoid any scandal. He grabs Lizzie by the throat and warns her that she’d better not say anything either. He orders her to fix him a drink, but without warning she smashes him over the head with the bottle of whisky. As he falls to the floor, she tells him she needs to save the President, Major Eckert and the three English actors. But most of all she needs to save Parker from himself…

Having cleaned up the blood, Knox emerges from the lift and the TARDIS asks for further instructions. Very weakly, he orders the ship to abandon the flight plan and set a return path back to 1865 as it’s imperative they go back to where they came from…

Under the orders of Major Eckert, Ford straps the Doctor to a human spinning board left behind by Six Gun Sadie and Her Wild West Troupe, a previous visitor to the theatre. As Ford starts to spin the board, the Doctor warns Eckert that he’s not easily disorientated and has a stronger stomach than he might think. The Major explains that the usual modus operandi is to hurl knives at the person strapped to the wheel, but as he doesn’t have any knives to hand, he’ll have to use a derringer pistol instead. He points the gun at the Doctor and orders him to confess his part in the plot and reveal the names of his seditionist allies. The Doctor tries to convince him he has no information to give. He says there was a plot to kill the President, but neither he nor Dr Smythe were part of it. Eckert refuses to listen and fires the gun.

Lizzie races through the town determined to reach Ford’s Theatre and stop the Major from going through with his actions. Evelyn spots her from across the street and just has time to call out a warning as Lizzie steps into the road and is nearly hit by a horse and carriage. Evelyn catches the shocked woman as she falls to the ground. Clearly distressed, Lizzie thanks her and Evelyn remembers seeing her in the gin joint with Parker. Lizzie realises who Evelyn is and warns her to leave Washington immediately. She tells her Major Eckert is waiting back at the theatre to kill Evelyn and her friend, then Parker in then going to kill the President. Evelyn has heard enough and races off towards the theatre before Lizzie can stop her.

Eckert mocks the Doctor and admits that his aim must be slipping, but he reloads his gun and prepares to shoot again. Ford tries to stop him and points out that he’ll never get the information he wants if the Doctor is dead. Eckert turns his gun on Ford and orders him to continue spinning the board and the Doctor advises him to do as the Major says as he seems beyond reason. Suddenly Eckert speaks to Ford again, but this time his voice has a deep unearthly resonance and Ford realises he spoke without moving his lips. A low throbbing heartbeat can be heard and the Doctor asks Eckert if he’s alright. The Major seems to return to normal and in his usual voice he mumbles that he needs to stop the seditionists. Then his voice becomes alien again and he repeats the word “kill” over and over. Evelyn and Lizzie arrive on the stage and order Eckert to stop what he’s doing, but the Doctor says the man isn’t himself. Lizzie tries to persuade Eckert to abandon his plan and offers to return his letters, and her words seem to have a calming effect on Eckert, so the Doctor encourages her to keep going while Evelyn unties him. The Doctor warns them that Eckert is on a hair-trigger and the slightest disturbance could tip him right over the edge. The man is obviously being controlled by something - and the Doctor has a nasty suspicion he knows what it is.

Just as the Major fires, he yells out and falls through the trapdoor in the floor. The lever had been operated by Ford, who claims he’s only pretended to faint. Lizzie hopes he hasn’t hurt Eckert but they can see him breathing even though he’s unconscious. The Doctor realises the entity will soon regain control and suggests they use iron ore to bind it until its energy discharges. He and Evelyn remember from their previous encounter that its powers were earthed by base metal. Lizzie suggests they use handcuffs and says the Major borrowed her own pair earlier and has them in his pocket. The Doctor sends her and Ford down to secure Eckert but then Ford back up and tells them Booth’s body has gone. Evelyn confirms that Clara had mentioned seeing Booth alive and well this very afternoon. The Doctor says he may be animated, but he certainly isn’t alive. Knox says this explains everything and mentions Chung Ling Soo’s most incredibly illusion. The Doctor realises Ling Soo’s greatest trick wasn’t his magic, but his very existence. Knox confirms that the magician wasn’t Chinese at all, but American and he fooled everyone, even going so far as to use an interpreter when giving interviews. The Doctor demands that Knox tells him everything…

In the cellar, Ford tells Lizzie he can’t believe Booth was alive all the time and says he must really be a good actor. Lizzie knows Parker was certainly fooled and she can’t imagine what’ll happen when those two meet. Eckert starts to revive and Ford hears the heartbeat again so he tells Lizzie to grab the Major’s gun before he kills them both. Eckert mumbles to Lizzie about a terrible thing being inside his head…but then the deep alien voice echoes around the room. The voice says it seeks out despair and helplessness and makes its home inside the downtrodden and the lost - people like Eckert. To his horror, Ford realises the voice is now coming from Lizzie instead. The alien tells Ford the only reason he’s still alive is because it doesn’t want to attract the attention of the time travellers up on the stage. It orders Ford to handcuff himself to Eckert.

Knox realises he doesn’t have much time left and the Doctor encourages him to steady his breathing. He says he being sustained by a creature he found trapped in a crater of congealed iron magma on Mercury. He promised it one of his magical history tours if it would keep him alive long enough to come here and get inside the head of Booth, one of Earth’s most notorious assassins. The creature loved the sound of that experience, but then Knox contained it within his TARDIS and bound it with iron fetters, a caged beast at his command. It hasn’t escaped so they must be dealing with another entity. When he came here Knox had no idea that the Earth was peppered with the creature’s relatives, drawn here by the misery and pain caused by the American Civil War and clinging to humanity’s tragedy like barnacles. The moment Knox arrived, his creature reached out into the psychic ether and called out to its kin.

Knox knew he couldn’t cope with a second creature on his tail, so he planned to contaminate Booth with an extract of iron in the elderberry cordial, mixed with cyanide so that when the creature entered Booth‘s body, it’d be trapped there as surely as the one inside his TARDIS. The entity inside Lizzie joins them and reveals it was warned about Knox’s murderous plan so she made telepathic contact with Booth and told him to switch drinks with Knox. The cyanide made no difference to Knox, but the iron in his bloodstream severed his connection with the captive entity. All that business about Knox and Clara Harris was misdirection, the art of the illusionist. It wasn’t a coincidence the Doctor landed here - Knox was using Booth to trap the Indo and he needed to lure the Doctor here to make sure history didn’t go too far adrift, but Booth feigned death to escape them all and events have now gone beyond their control. Knox starts to cough and realises his final moment has come. In his final breath, he bequeaths to the Doctor his TARDIS and tells him the ship will answer to his voice and touch. He can even free the imprisoned entity if he wishes. The Doctor accepts and thanks him, then Knox dies and his body crumbles away. The Doctor pays tribute with a eulogy from “The Picture of Dorian Gray”, and although Evelyn thinks it was a bit unflattering, he believes Knox would have appreciated the analogy.

The Indo reveals that they now plan to take Clara Harris instead as she’s miserable and cold. Clara will be with Lincoln when Booth fires his bullet and will place herself in the firing line to sacrifice herself for her President. She’ll become a martyr, a saintly innocent struck down by the secessionist cause. Lincoln will avenge her murder and the attempt on his life and seek terrible retribution from the South, causing the Civil War to continue, even more furious and more bloody than before. It will act as a beacon of suffering to attract even more Indo. The Doctor says he won’t allow this, but the creature says there’s nothing he can do to stop it.

The Doctor asks the creature to let Lizzie go, but the Indo can sense her fear and knows her spirit will be completely crushed once she kills the Doctor. The Doctor has no wish for his death to be on her conscience and offers to let the entity enter his body instead. He alone has full control of Knox’s TARDIS and he says he’ll only release the imprisoned Indo if this one agrees to his terms. He also reminds the creature that he’s a Time Lord, so if they kill him he’ll regenerate, which means Knox’s TARDIS will no longer recognise him and its cousin will never be free. On the other hand, if a Time Lord willingly gave up his body to the Indo, all of history’s horrors would be theirs to visit and the collective suffering of countless billions on an infinity of planets could be theirs to savour. The only condition is that they must agree to leave this planet alone as it‘s suffered enough. The Indo agrees to his terms. Evelyn expects to join them, but the Doctor says he needs her to stay in 1865 as she’s the only one who knows what’s supposed to happen this evening and he needs her to set history back on its correct course. The future of humanity is in Evelyn’s hands…

The Indo becomes impatient and orders the Doctor to submit himself. He agrees and goes into a trance, then in a deep alien voice he tells Evelyn it‘s too late for goodbyes. The possessed Doctor turns to the TARDIS and commands it to open. He goes inside, relishing the idea of experiencing all of history’s horrors. Having been released, Lizzie starts to come to her senses and asks Evelyn what happened to Major Eckert. Evelyn catches her just before she faints, then watches as Knox’s TARDIS dematerialises…

In Lizzie’s room, John Parker finds himself being dragged back to consciousness by an angry voice. To his horror, he wakes up and finds John Wilkes Booth has come back from the dead and is standing over him. Parker pulls out a gun and warns Booth to get back, but Booth can see his foe is shaking so badly he probably wouldn’t be able to hit him even from six inches away. He tells Parker to put down the gun so they can talk business. He knows Parker had been searching his room earlier and it’s obvious he thought Booth was dead and was taking whatever he could get his hands on before the law sequestered it. Parker insists that he didn’t steal any money but Booth repays him the 50 dollars he owed anyway as he doesn’t want it said that he never settles his debts. Booth tells him he and his friends have a night at the theatre planned and he warns Parker to forget he ever met him and not to interfere if he knows what’s good for him.

Inside the Doctor’s body, the Indo admires the interior of Knox’s TARDIS. This will be their means of transport to the realms of infinite despair, but the Doctor says he needs to calibrate the destination settings. The Indo stops him and demands that he release their cousin first. The Doctor asks the ship where the other entity is being kept and then summons the lift for floor Gamma-7. He steps inside, but just as the doors are about to close, he suddenly realises that if he takes the entity down there with him, it too will be pulled in by the mass of iron being used to bind its cousin. He suggests the Indo pop out of his body for five minutes, but the creature refuses. The Doctor suggests a compromise and says the Indo can stay in the lift and the TARDIS can whip up some localised resistance to shield it. That way the creature can keep an eye on him while he’s freeing the other entity. The Indo agrees and removes itself from within the Doctor’s body. The Doctor asks the TARDIS to close the lift doors - and then suddenly he leaps out and watches as they close behind him, trapping the entity inside. He laughs as the creature bangs violently, but uselessly, on the doors. He orders the TARDIS to never ever open those doors again. The creature will be trapped for all eternity inside the metal box.

The Doctor returns to the console to change the destination settings, but for some reason he can’t access the controls. Just then the scanner comes to life and a recorded image of Knox appears, looking down at him with a fiendish smile. Knox explains that his TARDIS was instructed to revert to automatic mode five minutes after dematerialisation as he estimated that would be enough time for the Doctor to trap the new entity. He says it was noble of the Doctor to sacrifice himself for the greater good, but the ship is now bound for the iron crater on Mercury where they will all remain forever. He says goodbye and the recording switches off - then the control room fills with the sound of the “Can Can” playing at full blast. Knox’s image returns just for a second to tell the Doctor that he won’t be able to switch the music off - not ever!

Major Eckert orders Lizzie away under threat of being arrested. He storms off and Lizzie tells Evelyn that she’d hoped Eckert would like her again if she returned his letters, but he only tore them up and told her to leave him alone. She begins to cry and says she’s also worried about what Parker will do when he finds her. Evelyn says she has to get out of Washington and start again somewhere new where nobody knows her. All Lizzie wants out of life is a small plot of land and Evelyn suggests California, but she has no money. Evelyn admits that she’s in a similar position after the Doctor left her here without so much as a brass farthing. Suddenly Lizzie remembers something. She kisses Evelyn and tells her Parker left his money box in her room. She thinks he owes her that much at least, so she rushes off to collect it.

Then, to Evelyn’s amazement, the Doctor unexpectedly returns. They hug and Evelyn plants a big kiss on him, until he reminds her that it’s still 1865 and the people here aren’t used to such public displays of affection. He tells her about the trap Knox left for him from beyond the grave but says Knox hadn’t reckoned on him re-setting the TARDIS’s galactic positioning system to read Mercury’s Southern lava field as the corner of 8th Street, Washington DC. Knox’s TARDIS has just landed there, a mere two blocks away. Evelyn wonders how long it took him to think of the idea as there’s a touch of grey in his hair, but he claims it’s just a side effect of the entity possessing him. He says he then removed the TARDIS’s temporal shields and set it off into the Vortex, leaving the journey’s end unspecified. One day they may find out exactly how ageless and deathless the Indo really are. Evelyn says she hopes Parker doesn’t catch up with Lizzie, but the Doctor reminds her that both of them, plus Booth, Ford, Clara and Lincoln are all history to them. The theatre is starting to fill up and Evelyn wonders whether she should stay and witness history first hand, but the Doctor reminds her Knox is in the audience and if he spots them now, the whole business might start over again and become twice as complicated.

Before they go, Ford tells them how delighted he is to see the theatre so full of paying customers. Mr and Mrs Lincoln are due to arrive any minute with Miss Harris and Major Rathbone, so he hopes there won’t be any more strange and inexplicable occurrences here today. The Doctor assures him it won’t be anything they don’t already know about. Ford is relieved and says with all the comings and goings he was worried there might be a loose end dangling. The Doctor isn’t aware of any, but then suddenly Ford remembers his poor stagehand Pops. When he learns that Ford found the young man’s dead body in the props trunk, the Doctor insists on being taken there immediately.

Ford explains that he was tidying up this afternoon and found Pops body in the trunk all boggle-eyed and stiff with a silk cravat around his throat. Evelyn is reminded of the one Knox was wearing when he posed as Oscar Wilde. The trunk is now empty and the Doctor notices the lock has been broken from the inside. Evelyn assumes the entity must have somehow escaped and is now using Pops’ body, but the Doctor is certain that can’t be right. Knox may well be ashes and dust, but the Doctor suspects that during the time he was connected to the Indo he must have absorbed some of their powers. Knox has placed himself in Pops’ body which is now walking around, dead but not dead. Evelyn says they have to stop him, but the Doctor thinks he’ll be long gone by now. As they leave, the Doctor tells Ford he hopes the evening goes with a bang.