A propaganda soap opera complete with a hero and heroine, the hero going off to war, plays on the TV screens of war beaten Atrios, a planet whose people have been forced to live underground due to heavy bombardment of their surface.

In the TARDIS, The Doctor and Romana wonder about Atrios.

In contrast to the soap opera on the TV, the real war is horrid, causing rubble to fall in on the hospital levels and destroying among other districts, Area 6 and upper levels, with heavy casualties. A red uniformed, gold braided, white haired cranky Marshal wants to win this war over their enemies -- the people of Zeos, which Romana calculates as being the twin planet of Atrios, located on the edge of Helical Galaxy. The Marshal consults with his second, the more cheerful and heavy set Shapp. The navigation of their fleet is being blocked, the fleet is flying blind in space. The Marshal doesn't seem to care that the hospital wards 7 through 10 are destroyed. Princess Astra does and wants to go visit the hospital under the pretense of checking on them but really worrying for the young man she loves, Surgeon Merak. She concedes that she needs the Marshal's permission to leave after arguing that she wants this futile war to end via peace and negotiation with Zeos. The Marshal tells her it is his duty to bring this war to a successful conclusion and her duty to uphold the people's morale. The raid is over so the Marshal assigns a guard to take Astra to the hospital. Astra storms out, mad.

Merak awaits the Princess as the Marshal makes a TV speech to encourage the people, many of whom are lying on the floor of the hospital. Astra pretends to criticize Merak that people are lying on the floor but in reality wants to meet secretly with him to discuss negotiating peace with Zeos. Merak pretends to have to check Astra's wrist band, a radiation band which reads different colours if one is on an area of too high radiation. He and Astra are in love. The guard seems to overhear their talk of having sent message to Zeos. None of their messages were responded to or the messages never got through to Zeos. It seems as if Zeos is not even there. The Marshal talk of counter attack but the fleet is still lost.

The TARDIS appears in space, in parking orbit over Atrios, confusing Romana and the Doctor as they cannot find Zeos! The Doctor wonders why it is gone or moved... a time shift? There is an awful lot of zeroes in one reading. Millions of miles away they see a red ball of a planet... or something as the Doctor is not sure what it is. Romana wonders if this has something to do with the Black Guardian. She also thinks it would be a good idea if the Doctor, whom, of course, makes it like it is his idea, takes the TARDIS in on manual.

On Atrios underground as all are, Shapp gets a signal that he declares is Zeos's secret weapon. Marshal keeps touching his neck irritatingly and goes to a long full body mirror to talk to it about Astra and her removal. Shapp seems to overhear him. After this talk, the Marshal leaves, telling Shapp he has to attend to a matter of state.

The guard gets a message from the Marshal and escorts Astra but tells her that her trip to the children's ward has been cancelled--it has been destroyed. She worries about the children but he tells her they have been moved and are alive. He will take her to them -- in K block, which she believed closed down due to excessive radiation contamination. He lies and tells her it was clear now.

In the control war room, Shapp gets an unidentified target in range: the TARDIS. In the TARDIS, the two Time Lords, see immense heat on the surface of Atrios, the Doctor happy that it seems one can fry eggs on the street. Romana assumes a huge nuclear war but the Doctor chides her for seeing the worst in things -- someone could be having a huge breakfast party. He asks her why she always assumes the worst will happen. Romana answers, "Because it usually does." He asks her what happened to her optimism. She answers, "It opted out." The Doctor turns to K9 for support of his positive outlook. K9 tells him that optimism is the gesture of thinking the best under all circumstances -- an insane notion. The Doctor tells Romana to always assume the best until you find out the situation is really the worst. Romana asks what if it isn't the worst. The Doctor seems insulted, "It always is, the worst, always, right, K9?" The Doctor doesn't get his answer, "It's always difficult walking into these situations, you never know who's fighting who." Both Time Lords figure this war is over the most important part of the Key to Time -- the 6th segment.

The guard brings Astra to K-block and makes her go in, telling her he is only following orders. He locks her inside, using two heavy metal doors. Inside, she finds it empty. The Marshal shoots the guard at close range and kills him. Astra's radiation bracelet is flashing red.

When Marshal returns to Shapp, Shapp tells him the Zeon secret weapon is not moving. Marshal orders it vaporized and a missile is fired at the TARDIS. The Doctor calls it a welcoming party and tells Romana they will not dematerialize until the last moment in order to confuse the enemy. Romana puts the tracer into the TARDIS console and the Doctor gets the last three seconds from K9 before he dematerializes -- not realizing he was cutting it so close. The TARDIS just vanishes before impact.

The TARDIS appears in an underground cavern and the Doctor comes out, followed soon by Romana, "No, don't say it? Not another underground passage." The Doctor calls K9 to come out and stop sulking, there are no swamps or water this time. He tells K9 it is quite safe, just as a bomb goes off and shakes the entire area! K9 tells them they are 400 meters below the surface and radiation here is variable. They find the corpse thanks to K9. When Romana deduces he was shot at close range, The Doctor figures by one of his friends, "Which proves one can't trust anyone these days." Romana doesn't think she is going to like this place very much. At the double metal doors where Astra is and which the tracer leads them to, K9 cannot analyze behind it due to heavy lead shielding. Romana thinks they might find the Black Guardian. The Doctor says, "Will you come into my palor said the spider to the fly." Apt quote, they think. The Doctor instructs K9 to make a little hole in the door. Astra is sitting and sleeping...or dying.

Shapp, in the control room of war, taps the Marshal on the shoulder while the Marshal is consulting with his mirror and scares the Marshal. Shapp tells him of an alarm that tells them someone is breaking into the K block area. Marshal orders it sealed off and he will take care of it personally. No one else is to be involved. Marshal leaves the room, also planning to see to that traitor Merak.

The Doctor sees through K9's hole and spots Astra's eye. She asks for help. Bending down with Romana, the Doctor says, "Romana there's a... there's a man standing behind you with a gun..." he tells her to get her hands up. Marshal blames them for the death of the guard. Romana and the Doctor keep answering differently (like No and Yes for the same answer to questions from the gun toting Marshal). While K9 remains hidden, the Marshal takes the Doctor and Romana off. Astra lays down on the floor. Blasts hit and K9 is blocked by fallen timber and stone. He tries to find another way around to either the TARDIS or the Doctor and Romana.

In the war room, Marshal accuses the Doctor and Romana of being spies. The Doctor asks Romana, "Do we look like spies?" Romana laughs, "No." They will tell the truth and then he will execute them. Merak is brought in even though he has 100s of patients to attend to. Marshal blames Merak for Astra missing. He tells the Marshal he does not know the Doctor and Romana but agrees with them against this war. The Doctor takes out a whistle for Marshal to blow. Marshal gives it to Shapp to blow. When it doesn't seem to work (it is K9's dog whistle), the Marshal drops it to the floor but the Doctor picks it up. In answer to the Marshal's question of what he does, the Doctor offers that he runs a time tourism business, trips to battle fields both past and future. Romana puts in that it is very educational. The Doctor whispers to the Marshal he is looking for a key.

As K9 moves around the blocked areas in another hallway, a door behind Astra opens up and a black faced, featureless monster-man comes out. He picks up Astra and begins to pull her into the closet-like area he came from.

The Marshal asks if that is the Doctor's last word. The Doctor says, "No" while Romana says, "Yes." The Doctor looks at her, "No! I sincerely hope not." K9 is seen by the Doctor at the exit so the Doctor tells the Marshal off -- his having shot at them, convinced they were spies, and threats to execute them -- after a long trip that is just too much to bear. The Doctor orders K9 to hit the lights off and K9 fires his ray at the lights. "Goodbye Marshal," the Doctor orders Romana out. Merak runs out, following them. Romana runs, "Where to?" "Back to the TARDIS!"

The black hooded caped creature over Astra pulls her further into the cabinet and a door closes over the cabinet area. Inside, the Princess and the monster man vanish.

Romana gasps that there is no way out but the Doctor says, "There's always a way out! K9's watching our rear." Merak joins them and tells them he is in love with Astra which explains a lot to them. K9 is directed to open the door as Merak explains about the Marshal. They rush in after the doors are opened by the mechanical dog. Astra is gone and K9 keeps warning about the rising radiation levels. The Doctor tells Merak that people aren't dissolved by radiation and tells K9 to keep an eye on the wall. The Doctor figures they go back and find out what the Marshal is really up to.

The Marshal orders Shapp to trap K9 while the trio are on their way back to the war room. Shapp has picked them up on scanners. Shapp thinks K9 is partly metal, thus they can send it to a recycling shaft to the furnaces and turn it into scrap for the war effort. A light lures K9 into a compartment and seals him in. He is put on a conveyor belt toward the furnace. The Marshal orders Shapp to treat the others well, no softening up process, no brutality, and after Shapp leaves, the Marshal adds, "Yet."

K9 finds his temperature increasing as he heads for the recycling furnace.

As they walk in the halls, Romana tells Merak about the tracer and that she and the Doctor are here to find something but will help if they can. She also asks about jewellery Astra wore, thinking one of the bits could be the 6th segment. Guards stop them, demanding to take them to the Marshal but the Doctor wanted to see him anyway and leads the group, "Let's move." He goes into the war room and puts his hand out to Shapp and talks fast, "I'm the Doctor WHO are you?" The Doctor and Shapp go to the Marshal by the mirror which Shapp explains is the way the Marshal meditates. The Doctor wonders if he makes all his decisions that way, it is the first step to megalomania. The Doctor goes on talking about a ventriloquist, a dummy, and a chap that throws his voice, explaining ventriloquist to Shapp. The Marshal turns and welcomes the Doctor as a friend, telling him his coming has been foretold and expected. The war excludes all else and drives the Marshal. The Doctor says, '"I understand how you feel, Marshal." The Marshal says, "You are the one!" The Doctor says, "I am!" He then wonders, "I am?" The Doctor will the one to free the land. The Doctor finishes the speech "This blessed plot" from Richard the II but the Marshal veers from it. The Doctor frowns, "I preferred the original."

The Doctor need to know the basic situation, sits in a chair, slouches at first but rises to watch the fleet of Atrios which is at the Marshal's command and will be at the Doctor's command--a fleet the Doctor counts as six ships. Marshal orders the fleet to be raised to attack. Shapp says, with little enthusiasm, "Attack, attack, attack." The people do not know the truth that the fleet is inexperienced, brave but not the best pilots -- they lost the best a long time ago. The Doctor sees three of the six lights that represent the ships, go out, three of the fleet is all that is left, they knocking out one light from Zeos. The Marshal calls back the three remaining ships and tells the Doctor they need his help. The Doctor has the best hope for a weapon: peace! The Marshal wants the ultimate deterrent; the Doctor tells him he has a true military mind. At this, the Marshal thanks him. The Doctor wants his help in finding the sixth... the Princess Astra, he corrects in mid sentence (a clue!).

K9 is overheating in the duct belt.

The Doctor considers a parasol affair, a kind of forcefield where the Zeons cannot get in but the Atrios people cannot get out. To this the Marshal does not agree--he wants to get out to obliterate the Zeons. The Doctor rubs his mouth, "Well, there's always a snag, isn't there?" He needs K9 but Shapp tells him K9 is in the furnace by now. The Doctor is panicky and yells at Shapp to find the furnace. He runs and climbs into the duct. K9 falls off the end of the belt.

Shapp, Romana, the Marshal, and Merak wait outside a furnace door. Shapp has shut down the furnace but it takes weeks to cool down. The Marshal chokes Shapp, "The Doctor must not die -- not yet." Romana hears this and sees a small cylinder box on the Marshal's neck under his collar usually but out at the moment. The Doctor blasts out of the door along with smoke, holding K9 in his arms, "Warm for the time of the year!" He has learned how to do this from a firewalker in Bali, "They do this sort of thing all the time." Marshal looks how the Doctor is not even singed.

Back in the control war room, the Marshal apologizes. The Doctor says they all make mistakes, "Don't we, K9?" K9 snaps, "Negative." The Doctor proposes a one way forcefield but he has to get to know the enemy. This will be a sort of psychological barrier, a kind of Atroiphobia but do this he must meet a Zeon. The Marshal cannot arrange that. There are no prisoners, this is total war. The Doctor must think of something else then. He calls Romana over and they whisper; Romana tells the Doctor what the Marshal said and about the box thing on his throat. The Doctor and she wonder who is pulling the strings if the Marshal is just a puppet. Merak listens. They must find Astra but it could be a trap. Who is supposed to fall into who's bluff? Astra must be on Zeos but they can't contact Zeos and can't see it. The Doctor shows Romana something must be blocking the planet from their view of it. That would account for the orbital shift and whatever it is might be absorbing light or energy and may be camaflaged. It may be large or small. Romana asks, "Can you be sure of that?" The Doctor quickly says, "Well, how could Columbus be sure." Romana asks, "Who?" He counters, "Never mind about that." The Doctor sends Romana and Merak to find out about that mirror that the Marshal is so fond of talking into.

The Doctor talks to the Marshal about a power forcefield but they have no reserve power, no more reinforcements, and fires in section seven, collapses in section eight, and nothing left. The Doctor figures they need energy to neutralize mass which is all a forcefield is. K9 tells them the more energy they use, the more they will need--this would drain the planet until there is no planet.

The Doctor proposes he go to Zeos and get a Zeon and bring them back as well as rescue Astra. Suddenly they hear Astra's voice and see her on a TV screen. She tells them to surrender, hand over the Marshal, and talk peace with the Zeons, "Resistance is useless." The Marshal pulls the cord from the TV scanner. The Doctor says something about saving his own neck to the Marshal. The Marshal tells him to go to Zeos.

In a small room behind the mirror, a two way mirror, Romana and Merak find a skull. They overhear the Marshal speaking to it and declare the Doctor is a Time Lord.

K9 and the Doctor talk in the hallway, wondering why the Marshal told them about the only transmat cabinet on Atrios that goes to Zeos and why the Marshal would know about such a thing going to the enemy base! The Doctor says, "One of us is being very stupid." K9 says, "Affirmative, Master."

Romana and Merak run from the small room to warn the Doctor.

The Doctor pulls his scarf from under K9's treads, telling hi he will see him soon. K9 warns the Doctor not to go. The Doctor tells him to let him make the decisions. The Doctor goes into the cabinet and finds the cabinet area with doors that close over it -- just as Romana arrives with Merak; Romana yelling, "Doctor! Doctor, wait! Oh no, K9, it was a trap!"

Inside, the Doctor hears her, "Trap?" Two dark cloaked creature men grab him and force him into the cabinet where they light up and vanish.

Romana tells Merak if she had about two weeks to spare she'd explain transmatting to him. She intends to take K9 and Merak to use the TARDIS to get to the Doctor, who she thinks if on Zeos.

The Skull actually talks to the Marshal, telling him there must be no more attacks on Zeos. The Zeons leave the Atrios fleet alone and withdraw. Marshal feels this means he is winning as Shapp rolls his eyes on the Marshal without Marshal seeing it.

K9 tells Romana that the TARDIS isn't buried...it's missing.

The black entity man-monster tells the Doctor he is in his power totally now. The Doctor has had a black box put on his neck by two more creature men. The Doctor merely takes it off and looks at it, "What, you mean because of this old thing?" Shadow hisses and orders the Doctor put into a cabinet where the Doctor sits comfortably until the doors close and he starts lying to questions from the Shadow. With each lie, the electric zaps him and the pain grows. The Shadow asks about the key which the Doctor tells him has five pieces in the TARDIS, which the Shadow has brought to the dank dark area where the Doctor is being interrogated.

K9 sets to work on the transmat cabinet on Atrios and gets the doors open just as Romana has finished explaining things to Merak -- like about the tracer finding Astra and the mat to Zeos. Merak grabs the tracer, dashes into the doors, and says, "I'm sorry, Romana!" He vanishes to Zeos.

The Doctor makes quips about blackness and time pieces to the Shadow, who tells him he is not dealing with a fool. The Doctor notes that the Shadow failed to get into the TARDIS -- due to the TARDIS auto defense mechanism. He bluffs that the key to time parts one to five are kept in a sort of limbo in a limbo room! He can't take them out but can take the 6th segment in. The Shadow doesn't trust the Doctor and the Doctor certainly doesn't trust the Shadow. Shadow tells the Doctor he has waited a very long time for the Key to Time and another 1000 years is nothing but the Shadow knows the Doctor, having watched his "backdoor meanderings" and knows there is a "lack of patience" in the Doctor. The Doctor says, "That's right, fools rush in..." Shadow feels the Doctor will make a mistake so he leaves, vanishing with all his darkness and black hooded tall monster-men.

The Doctor won't go into the TARDIS yet so decides to look for the 6th segment.

On a strange space station with four arms and oval shaped egg like devices on the end of each arm, Astra has her hands up and chained to a rock wall inside the interior, a cavern-like structure. Shadow interrogates her, thinking that she, the only surviving member of the royal family, must know the secret that has been passed down. She doesn't know or she would tell him, she insists. On a rock-a screen of energy shows Merak. She yells for him but Shadow tells her that they are not near him -- they are not on Zeos.

On Atrios, Shapp has left the war room to go to K block to check on intruder reports. A technician tells Marshal that there is one ship left now, "Your escape... uh, your command module."

K9 destroys the door lock on the transmat cabinet and he and Romana go inside, vanishing to Zeos. Shapp follows them...right into the transmat. Shapp loses his voice for fear and cannot call back to the war room. He hides as the Doctor runs-slides by. The Doctor finds the tracks of K9 and Romana; Shapp follows him but the Doctor finds himself looking at Shapp's boots and ordered to put his hands up. The Doctor tells him he is not armed and tries to explain. Shapp thinks they are in the prohibited section on Atrios -- Section 11-B. The Doctor, hands and arms up high, says, "Shapp, old chap, we're on Zeos."

Merak, in the halls, finds Astra's bracelet and hides at a corner. Romana turns the corner and grabs his wrist and holds his neck, telling him she will let him go when he stops giving her trouble. He agrees and tells her the tracer reacted to the bracelet that Astra wore.

Shapp finds the place dusty, along with the Doctor, not irradiated, and the air clear. Shapp blows the Doctor's whistle for K9 to come. The Doctor asks Shapp if he ever saw any Zeons before. Shapp tells him before the war for trade... they looked like the people of Atrios except for their clothes. The Doctor asks about tall, emaciated creatures in long black robes. Shapp thinks maybe bio genetic warfare. The enemies use disintegration capsules just like the Atrios people, thus no prisoners are ever taken. K9 arrives, telling them he has been conversing with the Zeon commandant, glad to be in communication with something other than limited organic intelligences -- his own kind, for the commandant is a computer like K9! Shapp calls K9 in good mettle and K9 needs that explained by the Doctor.

On Atrios, the Marshal gives a final speech, victory or death, he will lead the final assault and bombs are loaded on his module spaceship. It takes off with the Marshal and a pilot.

The Doctor and Shapp meet up with Romana and Merak. The Doctor thinks the bracelet has been in contact with the 6th segment. Merak asks Shapp about Astra. Shapp tells the youth to exercise more self control, then goes prattling off, calling for the Doctor. As the four watch, K9 spins around before the door to the computer room. The Doctor has never seen him do that, which isn't to say it isn't not normal or something like that. K9 tells them to be silent. He then talks to the computer. Romana suggests the turning is some kind of identification ritual like the dance of the bees. When Merak asks what bees are, the Doctor gets deadly serious and snaps, sneers, "Insects with stingers in their tails!!!"

K9 puts his antenna to the device. The Doctor waves his hand up for Shapp and Merak to wait as he and Romana go into the computer room. But once inside, the Doctor calls Shapp in to meet the only enemy -- the computer which does it all. There are no Zeons on Zeos. Just minerals and circuitry in the computer which K9 names Mentalis. It is just doing its job. Shapp pulls his gun but one of three laser guns on the walls, strategically placed, zaps it from his hand. The Doctor picks it up for him. Merak comes in, prompting them to ask Mentalis about Astra. The Doctor asks K9 to ask it if her name rings a bell, "so to speak." All info about Astra is inaccessible. K9 relays what else it has told him -- the war is over and the next step is obliteration for everything.

The Doctor relates how they have several problems at once. Mentalis thinks it has won and is about to self destruct, blowing up everything, winners and losers -- the Armageddon factor. The Doctor tells Shapp that it never occurred to him and the Marshal and everyone else that a third party, an evil alien spectator is involved in this war. The Shadow.

The Shadow has a box put on Astra's neck and wants her to go meet her lover and orders her to smile. She smiles.

The Doctor and Romana figure they will have to dismantle Mentalis. Shapp keeps asking the Doctor questions, interrupting him over and over. The Doctor sends Merak off with Shapp to go to Atrios to delay the Marshal. In the halls, vampire-like, Astra's voice lures Merak away. Shapp is near the transmat cabinet, calling for Merak when a Mute creature, one of the henchmen of the Shadow, shoots at him. Shapp shoots it down but is hit and falls back into the transmat, not badly injured but vanishing to Atrios.

In the halls, ghost-like, Astra passes right through Merak, who falls and falls and hurts his head at the bottom of a deep hole. K9 tells the Doctor it is safe to proceed dismantling of Mentalis, the Doctor not sounding sure of K9. Romana assumes the Shadow built Mentalis but the Doctor asks where he is. Romana reminds him of his theory of the thing in between the two planets, blocking them from one another -- the Shadow must have his own planet. Romana is unsure the Doctor can stop Mentalis. He uses the sonic screwdriver to undo the screws. He opens a door which triggers an alert, "What have I done, K9?" K9 tells him. The Doctor seems to swear, "Blast!" K9 says, "Affirmative." Romana says, "It's like sitting inside a time bomb." K9 alerts them to the hostile craft approaching. The Doctor suddenly dives at the bottom of Mentalis's self destruct box tower. The guns move and Romana yells, "Doctor lookout!"

Marshal has the pilot arm all warheads in his spaceship, ready to fire on the planet Zeos. The Mentalis guns aimed at the control center, destroying it to prevent the Doctor from interfering with the countdown. Like a scorpion stinging itself to death. The Doctor yells, "TARDIS!" They run out. In the TARDIS, the two figure with five pieces, they might have had some power but don't--the Doctor now knows Guardian technology doesn't work that way. But the Doctor figures with the gap left by the only missing piece, the 6th piece, he can make a psuedo 6th segment.

Marshal ignores Shapp's calls to turn back, calling the bureaucrats peace mongerers. His ship gets closer to Zeos.

The Doctor in smock, makes a 6th piece out of chlorodine and it is unstable but should allow them a neutral timeless zone. Romana puts it in and locks it with the tracer. Nothing happens... at first. Romana thinks they've failed.

The Marshal, caught in the time loop, says, "Fire!" over and over. His ship approaches and then moves back and then approaches within the three second time loop. The Doctor just realizes he has stopped the whole universe, "Still they'll never notice." Someone somewhere will never notice he is constantly slipping on that banana peel. Romana asks why they are not affected. The Doctor yells that it can't affect the users, "...even the Guardians would have thought of that!" He tells her he now has absolute power. They can be gods for four hours or two. He takes his smock off and puts his jacket on. Romana suggests he localize the time loop by communicating with it. He orders it to do so -- to the space around the Marshal's ship but at the last moment, Romana reminds him to add the computer room of Mentalis. The Doctor comments he thinks he did that well. Romana says, "All power corrupts, Doctor." The three second time loop will stretch and break down. The Doctor adds, "Nothing last forever."

The Shadow makes Astra try to lure the Doctor to the Shadow and gain access to the TARDIS. Romana repeats the Doctor's words as for the need for urgency: the time loop has begun to stretch as they go into the halls.

Astra calls Merak like Mena in DRACULA. His leg was twisted in the fall and his head is bleeding. Astra is seen by Merak through a strange round energy screen. She reaches into it for him.

Romana figures whoever built Mentalis has a twisted mind.

In the hall, K9 sees Merak, "Halt who goes there?" Merak tells Astra about K9, who detects hostile presenses approaching. K9 drives the guards off and into the transmat beam room. Astra goes to the TARDIS, which Merak claims only the Doctor and Romana can get in. K9 is proud of himself for driving the Mute monster men off but a box device left in the transmat lures him in. It is issuing a galactic computer distress call. He goes in and the door closes, and he vanishes via the transmat.

The Doctor and Romana find Merak and Astra; Astra lying that she escaped the Shadow through a tunnel of light. She also, oddly, claims she would rather stay with the Doctor than go back to Atrios. She claims she feels safer with him. The Doctor demands Merak take Astra back to Atrios.

K9 backs out of the rock opening doors and finds himself not on Atrios or Zeos.

Astra just lets Merak fall down and leaves him alone, telling him she would like to stay and watch him die but she has more important things to do. When he claims she is not Astra, she calls him a fool. Two Mute Guards come out of the transmat and take Merak to it. They vanish as Shadow laughs and laughs loudly.

The Doctor and Romana cannot find K9. Astra is calling for the Doctor at the TARDIS. They see her there and are chased by Mutes. The Doctor just gets them inside the TARDIS. Astra lies about Merak being safe and stares at the Key. The Doctor thinks they have about one hour of real time before the time loops breaks down completely. The Doctor hoped seeing the Key would trigger some hidden memory for Astra, hoping she would know more about the 6th segment. He stops her from touching it, telling her it is hot. Romana sets the coordinates. The TARDIS goes to the oval-armed space station of the Shadow.

Romana and the Doctor cannot take the tracer out of the key to time but Romana says millions will die on Zeos and Atrios if they don't do something. The Doctor suggests diagonal thinking. He needs Astra's help as she has seen the third planet. She tells them her destiny no longer lies on Atrios. The TARDIS goes to the third planet. The Shadow commands Astra, "Bring me Romana." The Doctor sends Romana out alone with Astra, telling them he will catch them up. He follows but finds an intergalactic distress signal. K9 follows the Doctor, his eyes bringing back a picture to his new Master, the Shadow. The Doctor is fooled by an illusion of Romana and Astra and he walks through it. He hears Romana calling over and over and sees five Romanas. Romana and Astra follow the Doctor, Romana wondering why he is not answering her. Astra lies to Romana, telling her all the passages link up ahead, further on. The Doctor passes his own image as well as several glowing pairs of eyes on the rock walls. He tells the Shadow that he and Romana knew at once that Astra was under the Shadow's power. He also brags that "Romana can look after herself, she's a Time Lord." He tells Shadow they are both Time Lords sent by the White Guardian. Shadow has always known they were Time Lords. And as they serve the White Guardian, he serves the Black Guardian. "He who walks in darkness." Shadow tells the Doctor, he is in the Valley of the Shadow. The Doctor falls and falls...

K9 tells his new master that the Doctor is captured. A rock wall opens and Astra leads Romana through...to a mute guard with a gun.

The Doctor gets up and finds the distress call box, switching the annoying thing off with a hit. He hears digging and on the other side of a rock door on the floor, pushes against what turns out to be another Time Lord named Drax. Drax recognizes the Doctor at once, calling him Theet, Feet, or Theta Sigma or Feta Sigma, or all four at various times. The Doctor takes some time to recall Drax.

Romana is put in the truth chamber and zapped.

Drax is from the Doctor's class of '92, they were in course ten together and are now 450 years from Gallifrey. They took temporal theory together and only now the Doctor recalls him; Drax failed, the Doctor got his doctorate. Drax went into repair and maintenance -- anything, anywhere, anytime and has been all over the galaxy. The Doctor asks about cybernetics and guidance systems. The Doctor deduces Drax is helping the Shadow; Drax had no choice in the matter, "Do it or die," he said, didn't he? Drax sees his broken distress caller. The Doctor wonders where Drax got his peculiar speech pattern: cockney from Brixton, London, Earth about ten years ago he was stranded on Earth and had to make due. His TARDIS is on Zeos now but he has made tunnels all over. They go into one of Drax's tunnel homes and the Doctor sees a stabilizer component. He realizes Drax's TARDIS is not inoperable. Drax has been here for five years and could have escaped. The Doctor asks why--Drax is working with the Shadow. Drax was supposed to ask to make a run for it in the Doctor's TARDIS...it was all to be a trap he admits quickly. He didn't know it would be an old friend, the Doctor that would be the one he would have to dupe. The Doctor claims they are Time Lords, they should stick together.

Romana falls out of the truth cabinet, interrogated by the Shadow in his lair. She's told him all she knows and it is not enough. Romana tells him, "I'm not afraid to die." She sees K9 is under the Shadow's control.

The Doctor, in Drax's small room in the caves, tells him that to fix the machine he is working on he must fix the synaptic adhesion. Drax claims he has fixed 1000s of these and it is always the chronostat. The Doctor finds a tunnel leading to the upper chamber and hears K9 calling to him, calling him Doctor -- K9 always calls him Master. K9 comes to a grid and gives the Doctor instructions but when the Doctor tries to pull the box under K9's chin off, K9 threatens him with immediate death. The Doctor says, "Awwww, K9!" Shadow wants the Key for Romana, K9 tells him. The Doctor bluffs that he needs to consider it, drops the grid down, and grabs up K9 from behind and pushes him down the opening to Drax. Drax calls K9 a heap of junk and removes the box control device at the Doctor's instructions. Drax warns the Doctor to be wary of the Mutes as the Doctor ventures above on his own...and back right up to a Mute, who takes him away at gun point.

K9 calls attention from Drax, telling him there is a malfunction in his drive -- he is sideways. K9 threatens Drax to restore him or he will obliterate him. Drax does so, putting what he calls the little tin dog upright. K9 notes Drax's silliness, "Your silliness is noted."

The Shadow asks the Doctor for the Key to Time; Romana is zapped. Romana tells the Doctor not to do it, she doesn't matter, she calls to him. The Doctor yells, "Well, of course, you matter!" The Doctor has protected Atrios and Zeos. Shadow tells the Doctor he has seen the 6th segment of the Key to Time; the Shadow on the same quest as the Doctor. Instead of this puny war, the Shadow claims he and his master will set both halves of the entire cosmos at war with each other. He and his master do not want power but they glory in mutual destruction. The Doctor will fetch the key.

Drax finds that the problem with the long gun he has made is synaptic adhesion. He tells K9 to stay as he goes to find the Doctor in the caverns.

The box device is taken off Astra, whom the Shadow says has her destiny at hand. Astra asks who he is and he tells her, "The Shadow that accompanies you all."

Drax shoots himself with the gun and shrinks himself to the same size that he shrank the Doctor to. The Doctor avoids the mute, now a giant to him, as runs to Drax and yells he was supposed to shrink the Mute. Drax figures one of them can make a diversion while the other shuts the open TARDIS door -- Drax fingering the Doctor to do this. If Drax tries to make them larger while in the hole they are hiding in, they will die, filling up the crack. The Key to Time is overheating and the Time Loop is reaching the breaking point.

Merak and Shapp are in the War Room, Merak's head bandaged; Shapp's arm in a sling from the shot he suffered. Merak gets the idea to find out about Astra's mystery from her records on Shapp's computer.

The Marshal keeps saying, "Fire!" as he is still caught in the Time Loop.

The Doctor says of the 6th segment, "It must be Astra, she must have it."

The Shadow leaves Astra and Romana in the cavern, prompting Romana to say, "If he thinks we're just going to stand by after everything we've worked for...." Astra doesn't seem to care... she seems in a trance even though free of the Shadow's influence. She tells Romana she is the 6th child of the 6th princess of the 6th dynasty of the 6th Royal House of Atrios, her time of becoming, of transcendence, and metamorphosis is at hand.

Drax has a way in to the Shadow's cave but the tunnel is not yet finished. The Doctor and Drax talk about some nonsense such as "Small is nothing, big is better," and Drax mentions a pick and shovel in his slang. The two tiny Time Lords watch as the Mute opens the door, sent in by the Shadow but a light dispels them both away. The Shadow will dispel the light once he puts all the segments together with the 6th piece. Darkness will reign then. He gets the Key to Time.

Romana figures it out -- and says to Astra, "Well, you're in greater danger than even we've imagined."

Merak finds out the same thing -- there is a molecular anomaly buried in the royal house of Atrios, passed on from generation to generation. Astra's every living cell is part of the Key To Time's 6th segment. To save them all, Astra must be destroyed!

Drax and the Doctor hide in the small door on K9's side -- the new plan hinges on K9 being able to act. The Doctor tells him to keep it simple. As K9 takes off, the Doctor asks Drax if he has ever been to Troy -- Asia Minor (a reference to their sneaking into the lair inside a type of Trojan Horse).

A Mute finds the Princess Astra's head band in the matter transfer unit but this allow Merak to take its gun and force him to take him to the Third Planet. Merak takes its hood and cloak. Upon arriving on the Third Planet (he must have discarded with the Mute or knocked it out or something), he sees the Shadow with the Key To Time, walking with four more Mute men. The Shadow has waited for this since eternity began.

K9 blasts into the Shadow's tunnel. The Shadow is telling Romana about Astra, the 6th child of the 6th generation of the 6th dynasty -- she is the 6th segment of the Key to Time. Astra says, "I am ready." She puts her hand out and vanishes into the pieces, the 6th, her, becoming one with the other pieces and the tracer holding them together. Merak arrives as K9 breaks in, diverting Merak from being killed. The Shadow mentioned that he already ordered Merak's elimination. K9 tells that he will do it but as he comes in, he whispers to his real Master -- the Doctor. The Shadow will leave Romana and Merak alive for now as witnesses to his glory. Drax and the Doctor come out and Drax shoots the Doctor and himself back to full size. The Doctor takes the key to time and hits the Shadow with a light. Drax will leave via the transmat shop.

Merak follows the Doctor and Romana back to the TARDIS where he insists on finding Astra, even though Romana tries to explain. He goes off and the Doctor pulls Romana's arm to get her back into the TARDIS instead of following Merak to stop him from looking...and dying if and when the bomb goes off. Inside, Romana says, "We're murderers, first Astra, now Merak. We're just pawns here to do the Guardian's dirty work." She goes on to express her regret and anger that Astra was a living being and now she is just reduced to a component, no power, she says, should have that right, not even the White Guardian. The Doctor reminds her to dematerialize, "Romana, you get carried away!" He tells her if they don't act now, millions will die and this time it will really be their fault.

There is ten seconds on the time loop now. The Doctor and Romana run out to the Mentalis room where Drax joins up with them again. Drax thinks the wire to cut is the green wire and fumbles around looking for a piece of paper before yelling it out to the Doctor, who cuts it with a second to spare.

K9 and Drax already found Merak...he will live. Romana tells the Doctor, "I have the feeling we're forgetting something." The Doctor can't think of what, "The Marshal!!!" They run for the TARDIS with Drax as the Marshal fires his missiles on Zeos. But the missiles don't center on the planet; instead they fly up to the Third Planet-or space station of the Shadow's. It blows up and apart, the Shadow calling his master, "Sire, I have failed. The Doctor has accomplished his mission -- he has the Key To Time." The Black Guardian snivels and sneers at him, expecting no less than failure from the Shadow, whose death has already figured in his designs, and who plans for the Doctor to release the Key to Time to him -- and then all chaos will break out.

In the TARDIS, with the door still open, the Doctor waves his arms up, "Well shot!" Romana smiles, "What did you do?" He tells them about a defense forcefield with a millisecond between the Marshal and Zeos so that the missiles were bounced to the Third Planet. K9 and Drax agree that the Doctor should have told them about this, could have told them. The Doctor says, "Well I'm sorry...I don't know why I'm apologizing for... I've just saved your lives." The Doctor asks if they can drop Drax off somewhere...he tells them he has a job now -- reconstruction over war damage...with the Marshal, who doesn't know about the deal yet...but will in a half hour's time and it will be a 50-50 deal but Drax admits he will make it 60-40." Drax goes, "Remember me to Gallifrey." After bidding him bye bye, they plan to set the coordinates for Gallifrey.

The Doctor starts to realize, "We have the power to do anything we'd like -- absolute power over every particle in the universe...everything that has ever existed or ever will exist... As from this moment," he looks at Romana and moves toward her menacingly, "Are you listening to me, Romana?!" Romana backs away a bit, "Yes, of course, I'm listening!" The Doctor cuts in, "Cause if you're not listening I can make you listen! Because I can do anything! As of this moment there is no such thing as free will..." his eyes roll up into the back of his head and he talks in a demented voice, "...in the entire universe there's only me and my will... because I POSSESS THE KEY TO TIME!"

Romana asks if he's all right. He answers in his normal voice, "Well, of course I'm all right but..." he goes on into a long explanation that he was just showing her that if he didn't think he was all right or if someone else wasn't...or something...it was supposedly just an act. Roman hits him on the shoulder. The sooner they hand the Key to Time over to the White Guardian the better.

The screen opens and the White Guardian seems to appear but it is really the Black Guardian in disguise. The Doctor asks Romana if it is a pleasure to see the Guardian again and she doesn't answer, telling the Doctor that is not the President. Romana should be careful who she's talking to, the Doctor tells her. She apologizes. The Doctor thinks the Guardian will stop the universe and restore the balances of good and evil in the whole universe. The Doctor keeps addressing the Key to Time, then stopping and asking annoying questions of the Guardian, then asks about the living sixth segment..Astra and how she will be imprisoned forever. The Guardian tells him it is regrettable, alerting the Doctor into activating the TARDIS's defenses. The Doctor thinks it would be a shame for the universe if he were colour blind. The Guardian coalesces into the Black, his eyes crossing. The White Guardian would never had had such a callous disregard for human life. The Black yells, "Doctor, you shall die for this!" He threatens to destroy the Doctor, to disperse every part of his being to the furthest reaches of all eternity. The Doctor would like to stay and watch him try but, "...you know how it is, places to go, people to see, things to do."

The Doctor tells Romana to dematerialize just as he snaps the tracer. The Key disperses all over space and time, scattered into fragments it seems. Astra is safe again, on Atrios, and standing over Merak's bed.