Journey’s End was the thirteenth and final regular episode of the fourth series of Doctor Who. It was the second episode of a two-part story, preceded by The Stolen Earth. This episode marked the last appearance of Donna Noble as a companion. It also had an open ending, which was quite different to how the previous seasons of the revived series ended; they each led into the next season’s Christmas special, but this one did not. However, several issues were concluded: the Cult of Skaro had been completely wiped out in this episode with Dalek Caan’s death, and the relationship between Rose Tyler and the Tenth Doctor also received closure in the form of a unique regeneration where the Doctor did not physically change, but rather, served as the genesis for a half-human clone.
The Tenth Doctor’s regeneration is nearly complete. Donna Noble, Captain Jack Harkness, and Rose Tyler are barely able to watch due to the light. Suddenly, the Doctor directs the rest of the regenerative energy into the container housing his severed hand. Rose, Donna, and Jack are confused, as the Doctor has not changed. The Doctor explains that he used the regeneration to heal himself from the Dalek energy blast, but siphoned off the remaining energy that would have changed his appearance and personality into his other hand — a matching biological receptacle. The Doctor says he didn’t want to change; Rose is relieved that “her” Doctor is still there and the two happily embrace.
Meanwhile, Sarah Jane Smith is covering her head with her arms, waiting to be exterminated by the Daleks, but with flashes of blue light, Mickey and Jackie appear beside the car and they blast the Daleks to pieces. Sarah Jane gets out of the car, shocked, but immediately hugs Mickey. He jokes, “We Smiths got to stick together”. Jackie introduces herself, but asks, “Where the hell is my daughter?” Over at Torchwood, Gwen Cooper andIanto Jones shoot at the Dalek, raging. But they notice something strange and they cease fire. They walk forward cautiously and see their bullets hanging in the air, as if stopped by an invisible wall. Gwen reaches out slowly to touch it — she can’t, but her finger makes a ripple in the air; it’s a time lock that their deceased co-worker Tosh was working on. However, while the Dalek is locked out, they’re locked in.
Elsewhere, a patrol of Daleks have found the TARDIS. Inside, the Doctor prepares to take off with his companions to figure out a strategy. However, right as he throws a switch, the Daleks uses a temporal loop to make the TARDIS powerless. They then take it to the Crucible. Upon arrival, the Supreme Dalek orders them to depart the vessel. Jack thinks they are safe because of the extrapolator force field the TARDIS has, but the Doctor points out it’s not working: “Right now that wooden door is just a wooden door”.
The Doctor, Rose, and Jack exit. However, Donna becomes distracted by the sound of a heartbeat and, while she is looking back, the TARDIS door slams closed. The Doctor demands that Donna be released. The Supreme Dalek denies responsibility and the Daleks dump the TARDIS, to be destroyed in the centre-core of the Crucible. The TARDIS plummets down and begins to burn up. As the TARDIS interior explodes, Donna collapses near the severed hand. She hears the heartbeat again and touches the container, and energy flows between it and her. The hand bursts out of the container, and forms into a duplicate of the Doctor, who quickly de-materializes the TARDIS. A view of the TARDIS in the core is shown to Jack, Rose, and the Doctor, who believe Donna and the TARDIS to have been destroyed.
Sarah Jane, Jackie, and Mickey lay down their guns, allowing themselves to be captured and taken to the Crucible in order to find the Doctor. Martha Jones says her goodbyes to her mother and uses the Project Indigo device to take her to Germany, where one of five Osterhagen stations is hidden, and awaits contact from the other bases.
Aboard the Crucible, Jack creates a distraction by shooting the Supreme Dalek with his revolver, but the Dalek Supreme promptly shoots him down. The Doctor and Rose are taken to the vault where Davros is held. Rose is desolate; she doesn’t know she made Jack immortal as the Bad Wolf and that his immortality has allowed him to escape.
In the TARDIS, the new Doctor has dressed himself in the Doctor’s blue suit and has finished repairing the interior from its damages. He rambles on about how they have to be quiet — “not even drop a spanner”. Donna then asks if Time Lords can multiply like this — “Chop off a bit and grow a new one”. However, the new Doctor explains that there has been nothing like him before. He then notices that he only has one heart, like a human; he’s not too pleased with this, saying it’s “rubbish”. Donna tells the “spaceman” to watch what he says, and the new Doctor tells “earth girl” the same. Both of them are shocked by this; he’s absorbed some of Donna’s mannerisms. He then begins pondering what Davros could be doing with the planets.
With the Doctor and Rose contained, Davros explains that the twenty-seven planets form an energy pattern amplified into a “reality bomb”, able to break apart the electrical forces holding everything together, a creation Davros calls “the apotheosis of my genius!” Mickey, Jackie, and Sarah Jane have been taken with many other humans to a testing of the bomb, but they escape the test chamber just in time (unlike the other humans, who vanish out of existence). The effect of the bomb is shown to the Doctor. Both Doctors realise how it works. Jack finds his way to the three, and, with a warp star from Sarah Jane, creates a device that will implode the Crucible. Meanwhile, Martha makes contact with two other bases in China and Liberia. The Chinese counterpart wants to get it over and done with, but Martha, knowing the Doctor, first broadcasts a signal to the Crucible to give the Daleks a second chance. She vows to use the Osterhagen key to detonate twenty-five nuclear warheads under the Earth’s crust to destroy it and disable the reality bomb. The Doctor is horrified that Earth would ever construct what is essentially a giant self-destruct button. Jack and the others then contact Davros and threaten to destroy the Crucible with the warp star; however, seeing all his friends driven to such extreme measures gives the Doctor pause. Davros notices this and tells the Doctor that this is what he does to people: the Doctor may be a man who never carries a gun, but he turns ordinary people into soldiers in his war. Davros then asks the Doctor how many other people have died for him and/or in his name, and the Doctor is reminded of River Song, Astrid Peth, Jenny and many others who have died to help the Doctor. Davros laughs that this is his final victory over the Doctor, by showing him his true face.
The Daleks lock on to their respective positions and transmat Martha, Jack, Mickey, Jackie, and Sarah Jane to the vault where the Doctor and Rose are being held captive, thereby preventing them from using any of their devices to stop the Daleks. The Daleks then prepare to activate the reality bomb to wipe out all matter in this and every parallel universe through the rifts in the Medusa Cascade, but the new Doctor and Donna arrive in the TARDIS. Each tries to destroy Davros and the Daleks using a weapon created by the new Doctor, but both are stunned by shots of electricity from Davros’ robotic hand before they can use it; Donna is sent flying while the new Doctor is put in a force-field. Despite the revelation that Donna and the TARDIS survived, the Doctor is glum because the reality bomb is still counting down. The Doctor and his companions helplessly watch in horror as the reality bomb ticks down to 9…8…7…6…5…4…3…2…1…
Nothing happens. Suddenly an alarm blares. Everyone looks over to see that Donna has used the controls to disable it. She gives a long technical explanation as to how she did it; this is astonishing because ordinarily, Donna “can’t even change a plug”. The Doctor recognizes that the creation of the new Doctor has had an unintended side effect: Donna is now half Time Lord herself, sharing the Doctor’s intellect — she is the DoctorDonna the Ood saw coming. She explains that the meta-crisis that created the other Doctor had also affected her, but the effect had lain dormant, needing a little spark to start it — “Thank you, Davros!” Donna and the new Doctor free the others and, with the help of the original Doctor, disable the Daleks. They start to send the planets back to their proper time and space. The Daleks are left literally spinning round in circles, thanks to Donna.
The Doctors then get to work and use the magnetron to send all the planets back to their correct places. Davros attempts to stop them only for both Jack and Mickey to hold him at gunpoint. Turning to Dalek Caan, he demands to know why he didn’t foresee this. From Caan’s maniacal cackling, the Doctor suggests that he did see it. Caan admits that he had seen the Daleks for what they were, had seen all the evil they caused across time and space, and secretly aided the Doctor in their destruction.
The Supreme Dalek descends to the vault and accuses Davros of betraying the Daleks. Though Davros insists that Dalek Caan is the traitor, the Supreme Dalek declares that he will destroy them all and destroys the magnetron before they could send Earth, the only remaining planet, back. As Jack destroys the Supreme Dalek, the original Doctor races into the TARDIS to replace the broken machine. Realizing that Dalek Caan has seen the end of the Daleks, has been manipulating time to achieve this, and knowing that, even without the Reality Bomb, the Daleks can still take the universe by force, the new Doctor uses the remaining machinery to destroy all the Daleks and their fleet. All around them, Daleks and their ships begin to self-destruct. The original Doctor is outraged at the new Doctor. The companions flee into the TARDIS. When the original Doctor offers to save Davros, he refuses. Gesturing at the destruction around them, Davros shrieks back, “Never forget, Doctor, you did this! I name you forever! You are the Destroyer of Worlds!” — an epithet the Daleks have long associated with the Doctor. Davros howls in fury as the flames surround him, while Caan ominously predicts again, “One will still die…”. Unable to save either of them, the Doctor flees into the TARDIS just before the Crucible is destroyed.
The Doctor comes up with a plan: he’ll use the energy of the Rift as a rope and the TARDIS as a “tow truck” to move the Earth back where it belongs. With the help of Torchwood’s Rift Manipulator sending the energy, Mr Smith roping it around the TARDIS and K9 supplying Mr Smith with the TARDIS’ base code, the Doctor is ready to go. However, he has a surprise for his companions. He explains to his companions that the reason that he has so much trouble piloting is that a TARDIS is normally piloted by six people, and he has had to do it all on his own. He lets Sarah Jane, Rose, Mickey, Martha, and Jack help him pilot while his clone, Donna, and Jackie watch — he specifically did not want Jackie to help, aware that she is not known for her intellectual prowess. The Doctor flicks a switch and, wonder of wonders, the TARDIS begins to fly with the immense Earth following behind. In Bannerman Road, Luke holds onto K9 and cheers as the room shakes, Ianto and Gwen holler in delight in the trembling Torchwood Hub, Sylvia and Wilf frantically try to stay on their feet and Francine takes cover beneath her kitchen table. With Donna and Jackie watching, the Doctors and companions work the controls until, with a great shuddering halt, the Earth stops and begins to spin, with the Moon hovering in to resume its own orbit. As the Children of Time celebrate in the TARDIS, Wilf, Sylvia and Francine revel in the sunlight and Earth celebrates its return home.
With Earth back in its proper place, the Doctor’s companions leave the TARDIS. Sarah Jane points out that the Doctor considers himself a lonely man, but he has the biggest family on Earth: his companions. She then leaves, concerned about Luke. The next to leave is Jack, but before he goes, he is stopped by the Doctor — “I told you, no teleport” — and has his vortex manipulator disabled yet again. Martha leaves with Jack, who tries asking her to join Torchwood. Mickey also departs. He had initially stayed in the parallel world to be with his grandmother, but she has since passed; he now wants to stay in his home dimension, though he’s guessed that the Doctor will be sending Rose back to her parallel world.
Using a closing rift, the Doctor returns Rose and Jackie to the parallel world and leaves the new Doctor with her. The original Doctor explains that by destroying the entire Dalek race, the new Doctor has committed genocide. He sees the new Doctor as similar to himself after the Time War (“full of blood and anger”), and says that Rose had made him better. The new Doctor explains that having only one heart, he will age as a human and not regenerate; he could spend that one life with Rose. Rose, upset that it’s still not the same as having the original, asks both Doctors the words that the Doctor was unable to say to her when they last parted. The original Doctor refuses to actually say then, only responding, “Does it need saying?” By contrast, the new, half-human Doctor, having the same memories and feelings as the proper Doctor, whispers them into Rose’s ear, and they passionately kiss. The Doctor and Donna quickly depart in the TARDIS and the new Doctor and Rose watch, hand in hand.
Returning to their universe, Donna is eager for her and the Doctor’s next adventure together but finds she has trouble thinking without babbling random facts. The Doctor explains that the human brain cannot take in the Time Lord mentality: if she continues in her current state, she will die as her mind will burn up. In tears, Donna protests that she wanted to continue her adventures with the Doctor as “DoctorDonna” and was willing to spend the rest of her life with him. Saddened, the Doctor says that he is so sorry; Donna then realizes what he is about to do and begs him not to send her back. The Doctor then tells her that they had the best of times. Ignoring her pleas, the Doctor presses his fingers on Donna’s head, wiping her mind of all her encounters with the Doctor, rendering her unconscious as a result. Back in Chiswick, Wilfred is excited when there is a knock on the door thinking Donna has returned home but his happiness turns to horror when he finds the Doctor outside with her still unconscious, asking for help.
The Doctor tells Sylvia and Wilfred everything that happened, and warns that she must never be reminded of her time with the Doctor or she will die. Sylvia tells the Doctor that the Earth’s journey through space is currently all over the news, but the Doctor answers it’ll only be a story to Donna — another event she missed. Wilfred is upset that Donna has forgotten all the wonderful things she did, the people she met and the places she visited knowing that she had become a better person for all of them. The Doctor states that the Donna that traveled with him is “dead”, fulfilling Caan’s prediction. However, he adds that the universe will be singing songs about Donna, who was, for one shining moment, the most important woman in the entire universe. When Sylvia tells the Doctor that Donna is always the most important woman to her, the Doctor makes a point of telling Sylvia to try showing her love more often.
As Donna recovers consciousness, she storms downstairs and starts laughing about her being asleep, but to her now, the Doctor is a stranger. She shows no interest in the Doctor and chats on the phone to her friends, who are all talking about the Medusa Cascade incident, to which Donna thinks that her friends were either drunk or that she slept through it. Sylvia tells the Doctor he should leave. Outside, the Doctor tells Wilf that the rain is the result of the atmospheric disturbance created when the Earth was moved back to its proper place but, like everything else, it will end eventually. Wilfred asks the Doctor who he’s got now, and asks him what happened to all his friends. The Doctor tells him that all his friends now have someone else, and that’s fine with him. Wilfred promises he will look out for the Doctor every night while he looks at the sky on Donna’s behalf. The Doctor quietly thanks Wilfred, then returns to the TARDIS; Wilf solemnly salutes as it fades away.
In the TARDIS, the Doctor watches the time rotor as he sets a new course. He tosses aside his rain-drenched pinstripe coat, leans on the TARDIS console, and stares off into the distance; deep in thought, heartbroken and having never felt so alone.