Fearing the worst, the Doctor and Donna take the TARDIS back to Earth, and arrive in London to discover that despite their concerns everything seems to be fine. The Time Lord explains that if Rose is able to travel between dimensions then the walls of reality are beginning to crumble – everything is in danger but he is not sure how. As he and Donna hurry back inside the ship they are unaware that a tremor is mounting outside. The turbulence increases as the roof tiles of houses begin to shake and fall – something is happening…

Inside the TARDIS Donna speaks with the Doctor, claiming that whatever threat may be approaching, at least he is about to see Rose again, and for that he should be glad. He agrees but his merriment is short-lived; seconds later the ship rocks violently. The Doctor hurries to the doors but upon opening them finds only space – the Earth has gone…

Far Across The Universe…

New York
At UNIT HQ, Martha Jones has been thrown to the floor by a sudden jolt of turbulence. She gets to her feet and checks that her colleagues are all unharmed, assuming the problem to be an earthquake. One of her friends, Suzanne, tells her to look at the sky, alarmed by what she sees out of the window.

Cardiff
In the Torchwood hub, Captain Jack Harkness, Gwen Cooper and Ianto Jones are also recovering from the shock. Worried about the Rift above the city, Jack hurries outside whilst his colleagues check their computers – the quake has impacted far beyond South Wales.

Ealing, London
Inside 13 Bannerman Road, Sarah Jane Smith and her adopted son Luke are equally disturbed by the shockwaves, having been thrown to the floor of their attic. After Luke identifies the blast as a cross-dimensional special transference, Sarah glances out of the window and notices that everything has gone dark, despite it being early morning. She calls on her alien computer, Mr Smith, who he tells her to go outside and look up at the sky.

Chiswick, London
Wilfred Mott and Sylvia Noble step outside of their house and onto the road. Wilf is convinced that aliens are at work once more, and his fears are confirmed when he and his daughter look skywards, amazed by what they see.

On another street, not far away, a piercing screech is heard and in a flash of light Rose Tyler appears, brandishing a large gun. She proclaims that the trouble has only just begun and then looks to the heavens, where a collection of new planets has appeared. The Earth has moved…

Inside the TARDIS, Donna worries about what may have happened; assuming her planet and her family have been destroyed. After finding no trace of the Earth on the TARDIS scanner, the Doctor realises he is going to need help, and tells Donna that he is taking her to the Shadow Proclamation.

Back on Earth the Torchwood team try to determine what has happened to the Earth. They detect that whoever has moved the planet has rigged a protective shield around it, keeping the air and heat from escaping – they want the human race alive. Ianto notes that twenty-seven new planets have been found in close proximity, as well as a large mass at the centre of the web.

In Ealing, Mr Smith tells Sarah that the unidentified mass is artificial in construction – it is a spacestation. As Luke phones his friends, Maria Jackson and Clive Langer and checks that they are all right, Mr Smith reveals that movement has been detected close to the planet – a fleet of ships.

In New York General Sanchez of UNIT claims that the fleet numbers two hundred vessels, all of which are headed Earthward. The planet is now on red alert, UNIT are to take battle stations. Martha, meanwhile has been trying to call the Doctor but has not been successful, the signal is being blocked.

As the ships enter orbit, the streets of London descend into chaos, with mobs looting every shop and vandalising everything in sight. Rose walks alone, unnerved by what she sees around her, stopping only to disperse some thieves in a local electronics shop. When they are gone she sets up a laptop, monitoring the approaching fleet.

Sylvia and Wilf return inside their home to discover alarming news reports concerning the oncoming armada. Wilf has unsuccessfully tried to contact Donna, now fearing for her safety.

In Cardiff the Torchwood team begin to worry about what creatures might be contained in the ships when Jack receives a phone call from Martha, who is still trying to get hold of the Doctor. She reveals she has been promoted to medical officer for the top secret Project Indigo, which Jack already seems to have heard of.

Mr Smith alerts Sarah to an incoming signal from the approaching fleet, which she tells him to play. The message it reveals is heard all over the world, at UNIT HQ in New York, in the Torchwood Hub and in Sarah’s attic. As they hear the battle cry of the approaching invaders Sarah, Martha and Jack all realise they are doomed. The Daleks are about to descend upon the Earth…

As Rose wanders the streets again, witnessing the devastation of the Dalek Saucers at first hand, the Daleks themselves coordinate the invasion from the safety of their main base, known as the Crucible.

Meanwhile, in New York, Martha watches as the Daleks descend on the city, their ships swarming around at an alarming rate. General Sanchez tries to retain control but soon the Daleks begin to attack the building.

Whilst the Supreme Dalek enters the bridge of the Crucible and rallies the thousands of Daleks hovering before him, the Doctor and Donna, unaware of the carnage being brought upon the Earth, head toward the Shadow Proclamation, a sort of Intergalactic Police housed upon a giant complex of asteroids. When they land they are confronted by a squadron of Judoon, whom the Doctor speaks with in their native tongue.

Eventually he and his friend are taken to one of the main Proclamation officials, an austere woman with blood red eyes. She warns them that Earth is not the only planet to have been stolen from the sky; twenty-three others have also gone missing at exactly the same time. Donna, recalling her adventure in Pompeii, asks if Pyrovillia is one of the missing worlds, but the Judoon claim it is a Cold Case, the planet disappeared over two thousand years ago. Undeterred by this, Donna reasons that the sudden disappearance of the other twenty-four worlds may still be connected, as might the disappearace of the Adipose Breeding Planet.

The Doctor realises that Donna is correct, and explains that the planets must have been taken out of time as well as space. Taking control of a 3-D simulation of the lost worlds, he adds in those mentioned by Donna, as well as the Lost Moon of Poosh, and when they are supplemented into the group of lost worlds the configuration in which they are set out is automatically altered to sustain equilibrium – the twenty-seven lost planets taken have been specially selected for something, possibly as part of the construction of an engine. He thinks about the lost Earth and recalls how someone tried to steal it before…

Back on Earth the Valiant is overrun by Daleks to the point of surrender. As the Daleks land across the world Jack tries to contact Martha and warn her to get to a place of safety. However, she is instead ordered to accompany General Sanchez in order to activate Project Indigo. They arrive in an unpopulated area of the building and grab the experiment – which resembles a large backpack. Despite Jack’s warnings Martha mounts the device on her back. Before she activates it General Sanchez hands her a large circuit board – the Osterhagen Key, and tells her to use it when she has the chance. Martha initially declines it but reluctantly agrees to take it.

General Sanchez then disembarks to fend off the Daleks that are entering the building; as he is shot down Martha activates Project Indigo, disappearing in a flash of light. Back in the Torchwood Hub, Martha’s former colleagues ask what Project Indigo is. Jack explains to his friends that it is a teleport system salvaged from Sontaran technology, but has not been fitted with coordinates of stabilisation so is therefore highly dangerous. With no way of knowing what has happened, he can only assume Martha has been reduced to atoms.

On the Dalek Crucible, the Supreme Dalek orders that the humans be brought onboard. He then receives communication from a disembodied voice elsewhere in the base – a voice pitched somewhere between that of a Daleks and an ordinary humanoid being. The voice, which is apparently housed in a Dalek casing with a robotic hand, asks if any news has reached them of the Doctor, but none has. He then warns that the Daleks must not assume their invasion will go unchallenged. He explains that Dalek Caan has been uneasy. Indeed the former member of the Cult of Skaro, who’s casing is now broken and who’s mind is clearly unstable, warns that soon the Doctor will come…

At the Shadow Proclamation the Doctor continues to mull over the problem of the missing planets whilst Donna sits alone, still worried about her family. Inside her head she suddenly hears a pulsating heartbeat, which is interrupted by another member of the Proclamation, who provides her with water. She looks at Donna and cryptically tells her there was once something on her back, and then claims that she is not like other human beings. Donna dismisses this, claiming she is only a work temp. The alien woman then apologises for Donna’s loss, but not for the loss of her planet, she talks of the loss still to come.

After the woman hurries away the Doctor asks Donna if there was anything occurring on Earth that might have foreshadowed recent events. She recalls that the bees were disappearing, and the Doctor realises this is the key to solving the mystery. He explains that some bees are in fact aliens, who were migrating home before the disaster struck. The signal these bees emit is tiny but will lead them back to Earth. He traces this and discovers it is the same wavelength being used by whatever took the Earth.

He and Donna hurry into the TARDIS and, using the scanner, find the remains of a trail that will lead them to Earth. The Time Lord hurries outside to tell the Judoon and their austere commander, who claims the Doctor must lead them in the battle across the universe to recover the lost planets. Appalled by this idea he goes back inside the ship on a false pretence and dematerialises before he can be followed.

By now the Daleks are on the streets of London, rounding up everyone from their houses and exterminating those who show resistance. Meanwhile, Wilf has armed himself with a paintball gun and has taken to the streets with Sylvia, hoping to use the paint to blind the Daleks and render them useless. When they turn to go home again a Dalek confronts them and Wilf tests his idea. However, the creature simply melts the paint away to restore its vision and turns on the two humans. Just as it is about to fire it explodes, having been blasted by Rose. She approaches Sylvia and Wilf, confirming them as being Donna’s family. She tells them she needs them, and the three return inside the house, where she claims that they need to find Donna in order to locate the Doctor – who is their only hope of stopping the Daleks.

In the TARDIS the Doctor and Donna find themselves at the end of the trail, having stopped at the Medusa Cascade, a sealed rift in time and space the Doctor visited a long time ago. Donna asks what they do now but her friend has no answer – for once he does not know. Donna begs him to do something but she realises even the Doctor cannot help this time.

On Earth, the United Nations surrender to the Daleks. In the Torchwood Hub Gwen, Ianto and Jack are left to listen to the incoming reports, which identify that the human race is being processed – the Daleks are choosing selected individuals for testing. Just as all appears to be lost a voice begins calling out amidst the different transmissions. It is heard on Rose’s laptop, on the Torchwood computers and also by Mr Smith. It is Harriet Jones.

She establishes links with Torchwood and Sarah Jane but Rose, who has no web cam, is unable to communicate. Harriet boosts her signal to try and establish a third connection and eventually she succeeds – Martha is also listening. She explains that Project Indigo tapped into her thoughts, and when she teleported she ended up exactly where she wanted to be – at home. Now she sits with her mother Francine at their laptop.

Harriet introduces everyone, much to the protest of Rose, who wants to be involved as well but is unable to reach the others. The former Prime Minister explains that she has contacted them via the Subwave Network, a sentient piece of software built to track down all those who can help contact the Doctor without being traced by other aliens, such as the Daleks. Harriet developed the software after it was created by the Mr Copper Foundation.

Jack claims that the group needs a weapon to fight back, and asks Martha about the Osterhagen Key and what it does. Harriet interrupts and forbids Martha from using it, for she knows the damage it will cause. Sarah then interjects and asks Harriet why she is so keen to help the Doctor, when it was he who deposed her. She claims that what she did to the Sycorax Invasion was the right thing, but insists the Doctor is still required. Just as she warned him when they last met, a time has come when the Earth needs him but he cannot be reached.

Now able to join forces, Jack realises that the Torchwood Hub will be able to use the power of the Cardiff Rift to transmit the Doctor’s phone number into space. Luke then explains that with the aid of Mr Smith he and Sarah will be able to boost the signal by connecting every telephone network on Earth together. Ianto however has doubts, noting that when they start transmitting they will be detectable. Harriet confirms his fears and explains that the signal will be traced back to her, but this does not matter now.

Soon the combined forces of Torchwood, Harriet and Mr Smith are at work, beaming the signal out into space. After a few moments it reaches the TARDIS and the Doctor, formally solemn, now leaps to life. However, the Daleks have also detected the transmission and dispatch a squadron to seek the source of it and destroy whoever is responsible. Elsewhere in the Crucible the disembodied voice warns the Supreme Dalek that Dalek Caan’s predictions are coming true. The Children of Time are moving against them, but everything is falling into place.

As the Daleks arrive at Harriet’s cottage, the Doctor locks onto the signal and suddenly the TARDIS begins moving. Columns of flame burst from the floor as the ship is forcibly moved through time.

Harriet transfers control of the Subwave Network over to Torchwood and asks Jack to tell the Doctor that he chose his companions well. She then gets up and turns to see the Daleks entering. She tells them that their lack of understanding about humanity will ultimately defeat them, and then they exterminate her.

As the signal continues to transmit, the lost planets start appearing all around the TARDIS. The Doctor explains that the Medusa Cascade has been placed one second out of synch with the rest of the universe, creating a hiding place for the stolen worlds. He then turns to the console and establishes a link with the others using the Subwave Network – rejoiced to see everyone again, but somewhat disappointed not to find Rose, who is equally saddened at not being able to make contact.

On the Crucible, Dalek Caan childishly giggles, claiming that the Doctor has arrived. The disembodied voice speaking with the Supreme Dalek then demands to be given access to the Subwave Network, and he overrides it. As the Doctor fights to regain the connection he is shocked to discover the voice belongs to someone he thought long dead – Davros.

The other companions, including a very shocked Sarah, watch as Davros welcomes his old enemy, who assumed that he was destroyed in the first year of the Time War – he had tried to save him. Davros explains that it was Dalek Caan who managed to intervene, having emerged there after temporal shifting away from 1930s New York. Despite the War being Time Locked Caan managed to arrive there, at the cost of his mind. He saved Davros and the two went into hiding, where Davros began cannibalising his own body in order to breed a new race of pure Daleks. The Doctor claims that after all the time they have spent together and after all they have both lost, he has only one thing to say:

“BYE!”

He severs the connection with Davros and immediately the Daleks leap into action – the Supreme Dalek orders that the TARDIS be found and brought to the Crucible. Whilst Davros claims that the Doctor will soon travel to the Earth in search of his companions, Dalek Caan has another premonition – that the most faithful companion of all is destined to die…

Soon a Dalek Saucer is headed towards Cardiff to destroy Torchwood and the Subwave Network. However, instead of staying to fight, Jack contacts Martha. He uses the codes held in the Project Indigo device to reactive his personal teleporter wrist-strap and, after arming himself, bids farewell to his two friends. He promises he will return once he has found the Doctor and then leaves, just as the Daleks begin to break in.

In Ealing, Mr Smith locates where the TARDIS is about to land and Sarah hurries to find it. She bids Luke farewell and tells him she loves him, before hurrying to her car and driving away. In Chiswick, Rose is also making her farewells. She contacts her “Control” and asks them to teleport her to the TARDIS. She says goodbye to Wilf and Sylvia, who wish her good luck as she disappears.

Meanwhile, the Doctor and Donna land on a deserted street somewhere in London. The Doctor asks his companion what Rose said when she met her and she recalls a warning – the darkness is coming. He presses her for more information but Donna claims he can ask her himself. She nods over his shoulder and he turns to find Rose standing waiting for him at the end of the road. The two former companions run toward each other, but their reunion is interrupted when a lone Dalek appears from the shadows. The Doctor is hit in his side by a deadly Dalek ray and comes crashing to the ground, much to Rose’s terror. Before the Dalek can strike again Captain Jack appears and destroys it with his gun. He and Donna then run to Rose, who is leaning over the dying Doctor. Together the three companions pick him up and carry him to the TARDIS.

Back in Cardiff, Gwen and Ianto arm themselves with machine guns. Hoping to go down fighting like their former colleagues Owen and Tosh, they await the Dalek onslaught.

Inside the TARDIS Rose leans over the Doctor’s body. Donna begs to know how they can save him and Jack claims both he and Rose know what is about to occur. Devastated by this knowledge Rose looks on as the Doctor examines his own hand – it has started to glow…

On the streets outside, Sarah races along in her car. After a few moments she screeches round a corner and is confronted by two Daleks, who prepare to exterminate her…Likewise, in the Torchwood Hub, a Dalek manages to force its way inside. Determined to stop it, Gwen and Ianto open fire.

As Jack grabs Rose and Donna and holds them tight, the wounded Doctor staggers to his feet. Rose explains to Donna that when a Time Lord is wounded his body changes. Sure enough, a few seconds later the Doctor’s body explodes with light. Ferocious yellow and orange flames engulf his head and hands, as he starts to regenerate…

Although the regeneration may have started, this time it will not be so straightforward. Seemingly unchanged by the process, the Doctor stretches his arms out towards the jar containing his severed hand and siphons the regenerative energy into it. As his companions look on, somewhat bemused, he leaps back into action.

Outside, Sarah cowers in fear of the two Daleks about to exterminate her, but is saved moments later when Jackie Tyler and Mickey Smith appear, both brandishing weapons similar to the one carried by Rose. They destroy the two Daleks and Sarah clambers out of her car, as Jackie demands to know where Rose is.

In the Torchwood Hub, a Dalek advances through the entrance portal as Gwen and Ianto open fire. Although their bullets have no effect, they are stunned when the Dalek stops moving. Lowering their weapons they step forward and discover the bullets are suspended in midair, as if some force field is shielding them and freezing everything outside.

Back in the TARDIS, the Doctor examines his severed hand, which is now glowing with golden light. He explains to his three friends that he used some of the regenerative energy to heal the damage done by the Dalek but halted the process before he could be completely changed – therefore he is the same Doctor. When he is through explaining Rose steps forward and the two embrace. Donna suggests she and Jack do the same, but he is not so sure.

In the Hub, Ianto uses the computer to discover that the force field is a Time Lock, implemented by Tosh before she was killed. Torchwood is now suspended in a bubble, nothing can get in but they cannot get out without unlocking the Dalek sitting nearby. Jack is their only hope.

In London, the Daleks manage to locate the TARDIS and the Supreme Dalek orders for it to be brought to the Crucible. Inside the ship all of the lights go out and the Doctor realises they are trapped. As Sarah, Jackie and Mickey arrive outside to watch the proceedings they see the TARDIS disappear. Sarah realises they too must go to the Dalek Space Station, and with the trans-dimensional teleports used by Jackie and Mickey out of power for the next thirty minutes, she offers herself to the Daleks in order to be taken away. After a few moments Jackie and Mickey disarm themselves and follow suit.

Elsewhere in London, Martha prepares to activate Project Indigo again, claiming it is time she used the Osterhagen Key as instructed by General Sanchez. Despite her mother’s objections she teleports away, and arrives in Germany, sixty miles from Nuremberg. Getting to her feet she looks around – the area is swarmed with Daleks.

As the TARDIS is dragged toward the Crucible – the massive structure at the centre of the web of stolen planets – the Doctor turns to Rose, recalling that her parallel universe is running ahead of his own. He asks what happened in her world and she explains that the sky above the Earth was being claimed by darkness – the stars were going out one by one. She then tells him that her version of Torchwood managed to build a Dimension Cannon, which allowed her to cross dimensions in search of the Doctor. She discovered that the walls of reality were beginning to crumble – even the Void between dimensions has been decimated, something has been tampering with reality.

Recalling her previous encounter with Rose, Donna asks why she seemed so adamant that she was special in some way, and Rose tells her that when her Torchwood used the Dimension Cannon to measure different timelines, they all seemed to converge on her, which Donna finds unlikely, as she sees nothing special about herself.

Eventually the ship arrives and the Supreme Dalek orders the Doctor to step outside. Rose and Jack protest but the Doctor claims they cannot fight back – when they faced the Daleks before the creatures were half-breeds, now they are up against a full-blooded Dalek Empire, even the TARDIS will not withstand attack. As the three companions continue to talk about the situation, Donna stands alone, a strange rhythmic heartbeat sounding inside her head.

Preparing to face the terror outside, the Doctor turns to each of his three companions in succession and tells them they were brilliant, and together they step outside, all bar Donna, who seems overcome by the beating in her head. Suddenly the TARDIS doors close and she is stuck inside. The Doctor tells the Supreme Dalek to let Donna go but it claims not to know what is happening. Labelling the TARDIS as a weapon it orders for it to be destroyed, and the vessel is dropped through a trap door into the depths of the Crucible, with Donna still inside.

The Supreme Dalek explains that the TARDIS is going to be plunged into the core of the Dalek Ship, which will burn it to dust. Sure enough the ship is flung into the burning heart of the Dalek Base and Donna is left helpless as the roundels on the walls begin to shatter and flames start to billow from the heart of the ship. The Doctor, Jack and Rose are made to watch as the Time Lord ship starts to crumble. Inside, Donna is flung to the floor, and once again she hears a heartbeat, which appears to be coming from the Doctor’s severed hand. She reaches out to it and as golden light swirls around her, the glass case breaks. Recovering from the ordeal, Donna watches as the hand starts to grow. The golden light spreads across the floor and in a matter of seconds the body of the Doctor is lying on the floor, naked.

On the bridge of the Crucible, the three travellers watch as the TARDIS disappears amidst the burning core, and the Doctor is left defenceless. Outraged, Jack takes out a pistol and fires at the Supreme Dalek. The bullets have no marked effect and he is shot down. Unbeknownst to the Daleks and Rose, however, Jack is not dead. As the two remaining prisoners are led away to see Davros, the Doctor catches the very-much-alive Jack winking at him.

Despite it’s ordeal in the heart of the Crucible, the TARDIS has not been destroyed. With the New Doctor now dressed in a blue suit (as opposed to the brown one worn by his counterpart), and the damage to the ship repaired, he tells Donna not to make a sound or else the Daleks will be able to detect them. Donna, however, is more concerned about the cloned Doctor she saw grow from the hand in the jar. He explains that he was born from the regenerative energy unused by the Original Doctor, sparked into existence with the help of Donna. He is the first of a new species – a Time Lord-Human metacrisis. As he talks he begins to notice a significant change in his biology – he has only one heart.

Donna recalls the heartbeat she heard and the Doctor explains it is his own, echoing back in time and converging on Donna. Again Donna questions why she is at the centre of things and once again the Doctor tells her it is because she is special, a claim she still refutes. Apparently understanding the workings of Donna’s mind since the metacrisis, the Doctor begins to realise that Donna really does believe she is useless.

Suddenly things begin to clear in his head and he become conscious that there is more than sheer coincidence in the two of them being together. First she was brought to the TARDIS, then he met Wilf, then she found him again – and not only that, the day they found each other again it just so happened her car was parked metres away from where the TARDIS was due to land. Even now it seems the ties that bind them are not yet fully woven – they are heading towards the end of something…

Back on Earth, Martha makes her way through the woodland to a castle, where an elderly housekeeper greets her. She takes her inside and Martha prepares to set about her work. She enters one of the many rooms and approaches a bookcase. Upon uncovering a hidden computer panel she opens up the door to a lift, which will lead her to what she needs. However, the housekeeper has heard of the Osterhagen Key and what it will do when activated. She pulls a gun on Martha and threatens to shoot, but eventually Martha convinces her that she must be allowed to do as she was instructed and use the key. The housekeeper lowers her pistol and Martha steps inside the lift.

Onboard the Crucible, Jack is thrown into the incinerator, but manages to escape and runs off further into the ship. In Germany, Martha emerges in a small control chamber and sends out a message to any other members of UNIT who will be able to help activate the key.

Soon Sarah, Mickey and Jackie are all escorted onto the Crucible, along with a crowd of other prisoners. Down below in the Vault, Rose and the Doctor are held in two apparently invisible security cells. The Time Lord demands to know what is going on and questions why Davros has been left in the lower levels of the ship. He realises that his old enemy is still not in complete control of his Daleks; he is being kept as a pet.

Davros rises above the Doctor’s jibes and introduces his two prisoners to the remains of Dalek Caan, whom he says foresaw the two companions being together at this moment. Having flown unprotected into the Time War, Caan saw all of time itself and knows what is to happen soon – the end of everything is approaching, and one of the Doctor’s Children of Time will die. The Time Lord grows angry; demanding to know whom it was that locked Donna in the TARDIS. Davros takes delight in the mounting emotion, and again he turns to one of Caan’s prophecies – which declare that soon the Doctor’s true soul will be exposed. Davros claims that he and the Doctor will witness one final journey together, and tells him he has arrived in time to witness the testing of his new experiment – the Reality Bomb.

The crowd of prisoners are brought to a halt in a large chamber onboard the Crucible. When one of the group collapses and the Daleks are distracted, Sarah and Mickey take the chance to escape. They run and seal themselves away in another chamber and look on as Jackie, who has stopped to help the fallen woman, looks up to the ceiling far above, where a massive armament has been constructed. As the Supreme Dalek counts down to the testing of the device, alias Davros’ bomb, the Doctor begins to realise what the stolen planets are for. The formation of the planets creates a massive amount of energy, which the Reality Bomb concentrates it into a singularity – giving it enough power to destroy matter entirely. Onboard the TARDIS the Duplicate Doctor and Donna inspect scans of the Crucible and discover the same thing.

Back in the prisoner’s chamber, Jackie and the others look on as the device above their heads begins to glow. Mickey then realises that the teleporters he and Jackie are carrying have now recharged. He motions for his friend to activate the device and she beams away to safety, standing with Sarah and Mickey as the Reality Bomb is fired upon the other prisoners, reducing them to clouds of atoms.

Down in the Vault, Davros explains that the Reality Bomb cancels out the electrical bond between every atom, causing them to disperse. With the power of the twenty-seven stolen planets at his dispersal, his invention will be able to transmit a wave big enough to destroy any living thing in any universe or dimension – as Rose has already witnessed, the stars are about to go out.

As the Daleks prepare to unleash their cataclysm, the Supreme Dalek recalls all other Daleks to the Crucible to seek shelter. Leaving the planet behind, the people of Earth begin to think their worries are over, but as Wilf predicts correctly as he and Sylvia walk the deserted streets of London, the ordeal is not finished yet.

Still hidden from the Daleks, Mickey, Jackie and Sarah are shocked to discover Jack crawling around in the service shafts. After he and Mickey greet each other, Sarah declares that she has something to fight the Daleks with. She produces from her jacket a necklace, on which is hung a shining gem, which Jack identifies as a warp star. It was given to Sarah by a Verran Soothsayer, for use at “the end of days”. Jack explains that a warp star is essentially a giant explosion waiting to happen.

Back on Earth, Martha makes contact with two other UNIT officers, who together prepare to activate the Osterhagen key. However, Martha is not prepared to destroy the Daleks yet without first taking a leaf out of the Doctor’s book.

Inside the TARDIS, the Duplicate Doctor and Donna begin constructing a weapon to fight the Dalek forces with. Knowing that Davros’ genetic code runs throughout the entire race of Daleks, the Doctor intends to lock the Crucible’s transmission onto the evil genius, thereby wiping out the Daleks in a massive backfire.

On the bridge of the Crucible, the Daleks receive an incoming transmission – it is Martha. The link is sent down to the Vault and the Doctor makes contact. At last Martha explains what the Osterhagen Key is – a chain of warheads placed beneath the Earth’s crust – the final option if the human race’s suffering becomes too great to reverse. Realising the Daleks need all twenty-seven planets for something, Martha threatens to deprive them of one of them, thereby thwarting their plan and saving the people of Earth from an even worse fate.

Moments later a second transmission is received, this time from inside the Crucible itself. It is Sarah, Jack, Jackie and Mickey, who are threatening to use the warp star in order to destroy the Crucible. As Davros marvels at seeing Sarah again, so long after their first encounter on Skaro, Rose turns to the Doctor to find him looking far from happy. Dalek Caan claims the Time Lord’s soul is at last revealed, and Davros begins to goad his old enemy by claiming that despite his entire crusade for what is right and good, the man who abhors violence manages to take ordinary people and turn them into weapons and murderers. After revealing the fate of Harriet Jones, Davros questions how many people have died in the Doctor’s name; and the Time Lord cannot deny that the number is vast indeed. At last Davros succeeds in exposing the Doctor for who he truly is – the man who runs and does not look back for fear of shame.

The Supreme Dalek then orders for the Doctor’s companions to be brought to the Vault, and sure enough, before they can act on their threats, Martha, Sarah, Jack, Jackie and Mickey are all brought before Davros. He orders them to kneel and forces them to watch, as the Reality Bomb is primed for universal detonation. The Doctor pleads with him to stop but it is too late, maddened by his approaching victory, Davros begins giggling and laughing manically.

Just as all seems lost, Donna and the New-born Doctor appear in the TARDIS. The half Time-Lord, half Human runs forward with his weapon, but Davros is one step ahead. Firing a bolt of electricity from his robotic hand, he throws the Doctor to the floor and places him in a holding cell. Donna runs forward and grabs the fallen gun but she too is blasted back, falling against a nearby control panel. The gun is destroyed and Davros blasts such resistance as pathetic.

The final countdown begins and the Doctors and their companions look on. As Donna gets to her feet, somewhat dazed by her fall, the Reality Bomb prepares to fire, but it is stopped when suddenly the system shuts down. All eyes turn to Donna, who has used the control panel to shut down the device, much to the bemusement of the Doctors. Not finished yet, she then proceeds to disarm Davros’ robotic hand, cancel out the Dalek’s weaponry and close down the holding cells trapping the Doctors and Rose. Astonished by her newfound intelligence, the Original Doctor asks how this has happened and Donna explains that the metacrisis that created the new Doctor was two-way. As well as placing some human attributes in the new doctor, it placed some Time Lord attributes in her. With the intellect of a Time Lord and the instinct of a Human, she is capable of more remarkable feats than even the two Doctor’s can achieve. Working together the three of them begin disabling the Daleks all over the Crucible, whilst the other companions set about clearing the Vault.

With the Crucible disarmed, the Daleks malfunctioning and Davros held at gunpoint by Mickey, the Doctors and Donna begin sending all of the stolen planets home using a device called the Magnetron. Rose asks what has happened to Donna and she explains about the metacrisis, and how the new Time Lord genes inside her were only activated following the shock of electricity administered by Davros. Now, with effectively three Doctors at work, they can undo all of the Daleks have done and restore normality. The timelines that converged on Donna were waiting for this moment in time, when she would become the person who had the power to save the whole of reality.

Turning on Dalek Caan, Davros asks why he did not foresee this happening. However, Caan has not lied. He foresaw the end of everything, but it was not the end of reality, it was the end of everything Dalek. Seeing all of time, he understood the pain and suffering his race brought and he determined to stop them, buy ensuring the timeline that brought the Doctor and Donna to the Crucible was not altered, he could ensure she was in a position to stop Davros – it was therefore Caan who closed the TARDIS doors in order to make sure Donna was present to initialise the metacrisis.

Descending into the Vault, the Dalek Supreme opens fire and zaps the control panel, but is stopped from causing any further harm by Jack, who blasts it with his gun. The Doctors discover that the Magnetron has been wrecked and only one planet is left – the Earth – now they will have to use the TARDIS to take it home. Whilst the Original Doctor readies the ship, his counterpart continues work in the Vault, listening as Dalek Caan tells him to destroy the Crucible and end the reign of the Daleks completely. This he does, and uses what is left of the control panel to overload the Dalek’s power feeds, causing them all to blow up, including the one in the Torchwood Hub, which in being destroyed manages to break the Time Lock.

Angered by his counterpart’s actions, the Original Doctor ushers everyone back into the TARDIS as the Crucible begins to overload. Showers of sparks begin to fall and flames engulf large parts of the Vault. Seeing Davros and Dalek Caan sat alone across the chamber, the Doctor offers his nemesis safety, but he will not take it. As the station crumbles around him, Davros names the Doctor as the destroyer of worlds. He gargles in pain as the flames lick higher, and Dalek Caan is left to assert his last unfulfilled prophecy – one of the companions will still die.

As the TARDIS takes off, the Original Doctor contacts Torchwood and tells them to open up their Rift Manipulator device and allow all the energy to be picked up by the TARDIS. He then contacts Luke and Mr Smith and asks them to seal the link between the TARDIS and the Torchwood Hub. However, Mr Smith requires the TARDIS base-code numerals in order to do this, and registering that will take a long time. However, Sarah has a trick up her sleeve. Speaking into the scanner she calls for K-9, who appears in the attic and links up to Mr Smith, feeding him the data he needs.

Soon the connection is ready and the TARDIS is all set to tow the Earth home. However, this time the Doctor is not going to be piloting the ship alone. Positioning Rose, Martha, Jack, Mickey and Sarah at each of the console panels (he asks Jackie not to touch anything), and with he, his clone and Donna ready to assist when required, he explains that the ship is actually meant to be piloted by six people, but he has to make do on his own – hence his somewhat chaotic piloting style.

With everyone in place the ship is set in motion, slowly but surely pulling the Earth along through space. On the planet itself, Gwen, Ianto and Luke all whoop with joy, whilst the Doctor’s Children of Time work together at the ship’s controls to take the Earth back home – united at last. Eventually the Earth is returned safely, and celebration floods across the planet. Wilf and Sylvia dance for joy as light is returned and Francine Jones walks out into the open air to look again upon the familiar sky.

Landing the TARDIS in a park in London, the Doctor (in his original form) begins to say goodbye to his companions. Before rushing off home to see Luke again, Sarah chides her old friend for acting like such a lonely man, when in fact he has a far bigger family than many people on Earth. As she departs, Jack and Martha step outside; ready to return to their lives on Earth. After disabling Jack’s teleport and telling Martha to get rid of the Osterhagen Key system, he bids them farewell.

Next Mickey steps outside, having decided he no longer wishes to live in a parallel world, where there is nothing for him now that Rose is no longer his girlfriend and his grandmother has passed away. He thanks the Doctor for everything then walks off, joining Martha and Jack as they leave the park.

Finally, he decides to send Rose and Jackie home too, to the parallel world where they have now made lives for themselves. He pilots the ship to Norway, on the beach where he and Rose last said goodbye. Donna explains that soon the walls between realities will be closed for good, and Rose suddenly becomes desperate to stay with the Doctor. However, he insists that she now has a job to do – look after his clone. Born in battle and responsible for genocide, the Duplicate Doctor needs to be kept safe and stopped from doing wrong again. Just as Rose managed to save the real Doctor when they first met, she must do the same for his copy. However, with only one heart and no possibility of regeneration, this new Doctor will grow old and die with Rose – at last she can be with him forever.

Despite this, Rose is not convinced that the new Doctor is the man she fell in love with, and to test that she asks him to recall the words he meant to say to her the last time they met, he began by saying “Rose Tyler…” but was cut off from speaking. The Original Doctor claims the words he meant do not need to be said, but the Duplicate Doctor whispers them in Rose’s ear. They kiss passionately and the Original Doctor and Donna leave, returning to their own reality.

Inside the TARDIS, Donna theorises where she and the Doctor might go next. However, the Doctor knows that something is wrong. He looks on as Donna begins to get tongue-tied trying to recall people and places. Eventually it becomes too much for her and she leans forward, evidently in pain. The Doctor stands before her and asks if she knows what is happening. She claims she does. They both know that a Human-Time Lord metacrisis cannot exist because it is impossible to sustain. Knowing she may be moments from death, Donna laments that she wished to spend the rest of her life with the Doctor. Travelling together throughout the cosmos, they could have seen and done so much more, but now all of that is doomed never to happen.

However, the Doctor will not let Donna die, he has another plan. Donna begins to realise this and begs him not to send her back home. Despite her pleas, he hugs her tightly and tells her they had the best of times together. He apologises to her then clasps his hands to her head. With a horrifying gasp Donna’s body goes limp, and the Doctor is left holding her in his arms.

One stormy night on Earth the Doctor returns her home, where Wilf is waiting. They lay her to rest on her bed and then return downstairs to Sylvia. The Doctor at last explains what has happened – absorbing the Doctor’s mind was too much for Donna to cope with and it was beginning to kill her. To save her life he wiped her mind completely of all traces of the adventures they spent together – she is now returned to the woman she was before she met the Doctor – the Donna Noble he knew, the woman he helped her become, is dead.

He warns Wilf and Sylvia that they must never remind her of the time she spent with him, because the second she remembers she will die. Wilf protests, claiming (despite Sylvia’s remarks to the contrary) that Donna was better with the Doctor, and the Time Lord replies by telling them that there are worlds in the universe that exist in peace and happiness because of Donna, and for one moment she was the most important woman in the universe. Sylvia claims that she still is as she is her daughter, and the Doctor snaps by telling her to say that to Donna once in a while, if for nothing more than to make her feel valued.

Suddenly Donna enters, oblivious to what has gone on, assuming, as the Doctor predicted, that she has missed the ball and does not recall the extraordinary events that have just occurred. She says a half-hearted hello to the Doctor then goes to kitchen to phone her friends and chat banally. Sylvia then asks the Doctor to leave, and after one more goodbye to the woman he lived through so much with, he departs.

On the doorstep, Wilf watches the Doctor return to the TARDIS, but before he goes he promises to look up to the sky each night and think of him on Donna’s behalf, grateful for the wonderful things he showed her. As the Time Lord goes on his way, Wilf stands to attention and salutes him, and then returns indoors. Inside the TARDIS, the Doctor tends to the console. With all of his friends somewhere else with other people to care for, he walks quietly around the ship, alone once more…