With Cybermen on the streets of London, old friends unite against old enemies and the Doctor takes to the air in a startling new role. Can the mighty UNIT contain Missy?
Continuing from “Dark Water”, Clara Oswald is trapped with a Cyberman in the headquarters of 3W in St Paul’s Cathedral. As it tries to kill her due to her irrelevance, she manages to stop its attack by stating she is really the Doctor.
Outside, the Doctor reels from the revelation that Missy, the woman controlling the Cybermen, is a female incarnation of the Master. The public appears unconcerned by the arrival of the Cybermen, but UNIT, led by Kate Lethbridge-Stewart, turn up and surround the Doctor, Missy, and her group of Cybermen. The Cybermen take to the air using built-in leg jets and scatter over the British Isles. Missy reveals that 91 Cybermen – one for every major population area in the United Kingdom – have been released from St Paul’s to explode over graveyards in each populated area, releasing ‘Cyberpollen’ that will resurrect the dead as Cybermen. Similar events occur all over the world. UNIT renders both Missy and the Doctor unconscious and takes them into custody.
In the Nethersphere, the dimension where Missy has trapped the souls of the dead, Danny Pink has chosen not to “delete” his emotions (having been given the choice in the prior episode). He sees the Nethersphere environment going dark and asks the virtual assistant Seb what is happening. Seb reveals that the “cloud” that is the Nethersphere is dispersing, and the souls are being released back to their bodies via rainclouds. Meanwhile, Clara tries to use her knowledge of the Doctor to authenticate her claim, but fails to convince the Cybermen in 3W that she truly is the Doctor. She is saved by Danny, who is now a Cyberman but has retained his personality.
Aboard a protected UNIT aircraft, Kate reveals to the Doctor that, per United Nations emergency protocols, he has been designated “President of Earth” with full control of the planet’s armies. Cyberpollen is reconstituting the dead as Cybermen, but the Doctor is unable to get anything further from Missy about her plans for the Cybermen. He tells Kate and other officials on board that there is nothing they can do for Earth now. In the meantime, Clara awakens at a graveyard where Danny reveals himself to her. Danny asks her to activate his cyber-body’s emotion inhibitor, as he cannot stand the physical and emotional pain he now suffers.
Missy escapes her captors and kills UNIT scientist Osgood. The Doctor faces her as a horde of flying Cybermen attack the plane. Clara calls the Doctor on the TARDIS’s phone. Missy admits she is the one who gave Clara that phone number (“The Bells of Saint John”) to bring her and the Doctor together. Clara asks for his help to stop Danny’s torment, but the Doctor, fearing that Danny would then kill Clara, refuses. Missy then blasts open one of the plane’s cargo doors, sending Kate and the Doctor plummeting towards the ground to their deaths while she teleports to safety. The Doctor narrowly escapes by calling the TARDIS to catch him and break his fall, and he joins Clara at the graveyard. The Doctor still refuses to help Danny for moral reasons. He asks Danny about Missy’s plans, but Danny tells him that the Cyberhive cannot be fully accessed without the inhibitor. As the Doctor is hesitant, Clara insists that she be the one to do it. The Doctor reluctantly gives her his sonic screwdriver to turn the inhibitor on. Danny then reveals that a second rainfall is coming, one which will convert living humans into Cybermen.
Missy teleports to join them and gives the Doctor control of the Cyberarmy, as a birthday present. She explains that he can lead his own personal Cyberman army as a conquering force to save the universe from tyranny, such as that of the Daleks, as he has always wanted. The Doctor protests that no one should have such power. Missy taunts that he does not trust himself, and she wants to prove to him that they are fundamentally the same. After pondering the situation, and what sort of person he has become, the Doctor ultimately rejects the “gift” and passes the control bracelet to Danny, who is revealed to have kept hold of his personality through his love for Clara. Danny leads the Cyberarmy into the sky, where he and they explode, incinerating all the Cyberpollen clouds across the world, thus stopping the second rainfall and saving humankind.
Although disappointed that her plan has been ruined, Missy suggests that she and the Doctor can still become friends again and return to Gallifrey, which she claims has now returned to its original location. Furious over what has happened, Clara instead prepares to kill Missy with her own weapon. The Doctor, however, insists on committing the deed himself to keep Clara’s hands clean. He acknowledges to Missy that she wins. But, before he can fire, a solitary Cyberman vaporises Missy and gestures towards an unconscious, but still living, Kate Lethbridge-Stewart. The Doctor realises that this Cyberman is her father, the late Brigadier Lethbridge-Stewart, also with his humanity intact. The Doctor salutes his old friend (something Kate remarked earlier that her father always wanted from the Doctor), and Lethbridge-Stewart fires his leg jets and flies away.
Two weeks later, Danny contacts Clara from the Nethersphere as it begins to shut down. Explaining that there is only enough power in Missy’s control bracelet to bring one person back to life, Danny uses it to resurrect the boy he had accidentally killed while serving in the army. He asks Clara to return the boy to his parents. In the interim, the Doctor travels to the spacial coordinates given by Missy, only to find nothing there; Gallifrey remains lost. Some time later, Clara meets with the Doctor to tell him about Danny’s fate. Assuming Danny is alive again, the Doctor interrupts her with the news that he found Gallifrey and plans to return home, wanting to spare Clara’s feelings. Clara, in turn, says that she and Danny are going to settle down and resume their relationship. They bid each other goodbye.