On the planet Skaro, a woman, Darla, meets with the Doctor. He admits that he got her message and that not many people can contact him. She explains that she has a daughter, Hannah, in a Dalek prison camp, and asks the Doctor for his help in rescuing her. He demands to know who told her about him but Darla insists that it doesn't matter. Darla explains that she managed to escape but the Doctor points out that no one escapes a Dalek prison camp. He takes her hand and realizes that it's cold, and then tells her that it's a trap even though she doesn't know it. A Dalek eyestalk emerges from Darla's forehead and a Dalek weapon emerges from her palm and she uses it to stun the Doctor. A Dalek saucer arrives nearby and the Daleks announce that they have acquired the Doctor.
Amy is doing a fashion shoot when her assistant comes in to tell her that her husband is there. She insists that she doesn't have a husband but the assistant says that she does. Amy goes to see Rory in her dressing room and he gives her the divorce papers she has to sign. She does and he angrily stalks off, as the lights on the mirror flicker and Amy's assistant Cassandra comes in. A Dalek eyestalk emerges from Cassandra's forehead and she stuns Amy.
Rory gets on the bus outside and the bus driver converts into a human Dalek and stuns him. When Rory wakes up, he finds himself in a plain white room with Amy. He runs to the viewport and sees a Dalek fleet floating in space outside. Two Daleks escort the Doctor in and the floor moves upward, lifting them into a vast chamber filled with thousands of Daleks as well as the TARDIS. The Doctor tells his companions that they are at the Parliament of the Daleks and dares his mortal enemies to do their worse. Instead, the Daleks order him to save them.
A woman, Oswin, is in her quarters barricading the door and making soufflés. Something keeps trying to break in every night. The Daleks try to burst in, shrieking, and Oswin turns up the music to block out the noise.
As Darla enters the room, the Doctor paces around and takes in everything. The Daleks announce that they have arrived and Darla tells the Doctor that the Prime Minister will speak with him. She tells the Doctor that her memories of who she was are only reactivated if it facilitates her mission. The Doctor approaches the Dalek Prime Minister, a caseless embryo, and it asks him what he knows of the Dalek Asylum. He knows that it's a legendary planet where they lock up the insane and battle-scarred Daleks that they can't control. The Prime Minister admits that it is offensive to them to extinguish such pure hatred. A viewing port opens, revealing the Dalek asylum covering a whole planet. Darla tells them that millions of Daleks occupy the planet, which is fully automated. She plays music from Carmen
and explains that it is a signal they're receiving from the heart of the planet. The Daleks don't know what it is and order the Doctor to explain, and he admits he was playing in the orchestra. He tracks back the signal and contacts Oswin, who explains that she's the starliner Alaska
's entertainment director and stranded on the planet for the last year. The Doctor wonders how she's been holding off the Daleks and Oswin admits that she doesn't know. He also wonders where she gets milk for the soufflés.
The Daleks dismiss the conversation as irrelevant and cut off the signal, but the Doctor points out that if a starliner can crash there then the insane Daleks can escape. He points out that the Daleks have chosen not to destroy the asylum planet and Darla explains that the asylum has an impenetrable force field that can only be turned off from the inside. When the Doctor points out that a small assault squad could penetrate the force field, he realizes that the Daleks are too scared to go down. Darla attaches a device to his wrist, saying it will protect him from the nanocloud, and then ushers him into a gravity beam. They attach similar wrist devices to Rory and Amy, saying that the Doctor requires companions, and then shove them into the gravity beam.
The Doctor, Rory, and Amy find themselves on the ice planet as a human in a white parka looks on. He goes to investigate and finds Amy, alone. Harvey introduces himself and goes after Amy as she runs off to find the others.
A Dalek eye probe emerges from the snow and spots the Doctor as he recovers consciousness. He notices it as it plays Carmen
and Oswin speaks through it, contacting him. She explains that she hacked the Dalek technology, even though the Doctor says it isn't easy, and she explains that she's somewhere underground. Amy and Harvey arrive and Harvey says that another beam hit nearby. They find a deep shaft and get no response from inside.
At the bottom of the shaft, Rory wakes up and finds himself surrounded by Dalek casings. None of them respond to him.
Harvey takes Amy and the Doctor to a concealed escape pod and explains that it's one of twelve that came down from the starliner Alaska
two days ago. Amy points out that it's the same starliner that Oswin said she was aboard, and the Doctor remembers that she said she had landed a year ago. There are other crew inside, but the Doctor realizes that they're all long dead. Harvey insists that he had just talked to them but it's clear that they've been dead for a long time. He then realizes that he's been dead for a long time but he died outside and the cold preserved his body. A Dalek eyestalk emerges from his forehead and he advances on the Doctor, who sprays him with a fire extinguisher, driving him back into a closet. Amy locks the door and the Doctor explains that Harvey was converted by the nanocloud, turning any matter into a Dalek puppet. As the Doctor explains that the wristbands protect them, the corpses stand up and advance on them. The Doctor and Amy force their way past them into the forward cabin and seal the door, and she admits that she's missed that kind of adventure.
Oswin contacts them via the radio and informs them that she's hacked into the system, even though the Doctor insists that it's impossible. She has them check the floor for an escape hatch and the Doctor figures that it goes down into the asylum and someone escaped through it and sealed it behind them. As he opens it, the Doctor asks Amy about Rory and herself, realizing something is wrong between them. He's shocked when she tells them that they split up and Amy tells him that there's nothing he can do to fix it. Meanwhile, the Dalek drones pound on the door. When the Doctor checks on them on the view monitor, he discovers that one of them is wearing a protective wristband and Amy realizes that she lost hers.
Rory looks around and examines another casing. When he swivels it around, it slowly swivels back into its original position. It and the others slowly activate and stutter out "Exterminate." As they open fire, Oswin contacts him and directs him to a nearby door. Rory gets out just in time and Oswin seals the door behind him.
Amy and the Doctor climb down the shaft and the Doctor explains about nanobots and how they're rewriting her genetic structure, starting with her mind and memories. He points out that they're already working and that it's the fourth time he's had to explain it to her.
Rory follows Oswin's directions through the corridors and into a sealed room, and then jokingly tells him to take his shirt off.
The Doctor and Amy find the chamber that Rory occupied earlier and hear the Daleks in the distance. As he seals the door and calls to Oswin, Amy clutches at her forehead in pain. Oswin directs the Doctor to a computer screen with a map showing Rory's location, Meanwhile, Amy sees people from her past in the chamber and herself as a young girl, dancing. As the Doctor tries to work out how to get past the Daleks in the complex, he sees Amy walking away and goes after her. He tells her to concentrate and Amy realizes that she's looking at Daleks. They run to the shaft only to discover that the Dalek drones are coming down. The Doctor and Amy hide in the computer alcove and the Dalek behind them shuts down, too damaged to move. The Doctor demands that it identify him. When it does, he tells it to fulfill its standing orders to kill him. Unable to fire, it initiates its self-destruct and the Doctor programs it to move backward into the other Daleks, destroying them.
Rory feels the explosion and goes back to the chamber to investigate. The Doctor steps out, carrying an unconscious Amy. Oswin warns that Amy will soon try to kill them as she wakes up and slaps Rory. The Doctor wonders how Oswin hasn't been converted by the nanocloud and she says that she's shielded within her compartment. When the Doctor wonders why the supposedly automated complex is in such disarray, Oswin explains that she's been sabotaging the mechanisms in her spare time. The Doctor doesn't believe it, pointing out that she's an entertainment manager and couldn't get milk to make soufflés. Meanwhile, Oswin checks the database and asks the Daleks why they consider the Doctor a predator, but he insists he isn't.
The Doctor tries to come up with a plan and asks Oswin how fast she can drop the force field. She says she can do it quickly and wonders why, and the Doctor points out that there's a teleporter in the chamber. He starts boosting the power so they can beam off the planet to the Dalek ship before the Daleks blow up the planet the second the force field is dropped. The Doctor asks Oswin to drop the force field and come to them, and she wonders why they would wait for her. He admits there's no reason not to and Oswin sends him a map so she can come get her. When Rory asks if they're going to get Oswin, the Doctor says that they don't have a choice. He tells Rory to take Amy and teleport to the Dalek ship if things become too risky while he's rescuing Oswin. The Doctor tells Amy to remember what she can to hold back the conversion process and don't let them subtract love.
The Doctor goes through the corridors while Amy and Rory wait. Rory tells her that he's going to give her his wristband so that it will hold off her conversion and take longer to convert him, buying them time. He reluctantly explains that it will take longer to convert him because he loves her more. When she asks how he can believe that, Rory reminds her that he waited two thousand years for her. Amy slaps him and explains that she kicked him out because she couldn't have children after Demon's Run and he wanted them. Crying, she says that she gave him up and tells him not to touch her, but they realize that the Doctor has already given Amy his wristband.
The Doctor gets close to Oswin's chamber and she warns him that he's going to pass through Intensive Care. The chamber holds survivors of particular wars and the Doctor realizes they're Daleks that have survived him. They activate and recognize him, chanting his name, and the Doctor goes to the door out. It doesn't open and Oswin tries to find a release code. The Daleks move in on him but then shut down and retreat. Oswin boasts that she hacked into their telepathic net and removed all information they had about the Doctor. She then opens the door as the Doctor points out that even he hasn't been able to hack the telepathic net in the past.
The Doctor goes into the next chamber and then pauses. He asks Oswin if where she is looks real to her, and she insists that is. However, the Doctor tells her that she dreamed it because the reality is too terrible. He confronts a Dalek, chained in place, and it insists that she is Oswin and she's real. She was the one who climbed out of the pod and into the asylum, only to undergo full conversion.
The Oswin-Dalek breaks free of its chains and advances on the Doctor, chanting, "Exterminate!" It corners him and then hesitates, and Oswin asks why the Daleks hate him so much. He explains that he has fought the Daleks and Oswin knows that they have grown stronger because of their fear of him. The Doctor admits that he knows but he couldn't stop, and Oswin tells him that she's taken down the force field and the Daleks have begun their attack. She insists that she fought the Daleks and is human, and tells the Doctor to remember her.
As explosions rock the asylum, the Doctor gets back to the teleporter. Rory and Amy wait and both agree to wait until the Doctor arrives or die with him. They kiss and the Doctor arrives. When he can't get their attention, he activates the teleporter.
Aboard the Parliament ship, the Daleks detect an incoming teleport beam. The Doctor emerges from the TARDIS, explaining that he precisely aimed the teleport beam. However, due to Oswin's machinations, none of them recognize him. The Doctor smiles in satisfaction and leaves in the TARDIS as the Daleks wonder who the Doctor is.
On Earth, the Doctor drops off Amy and Rory and they go inside... together.
Aboard the TARDIS, the Doctor dances in triumph.