Continuing from the previous episode, the
Master and Missy capture the Doctor, but he had earlier surreptitiously reprogrammed the Cybernet to target
Time Lords as well, forcing them to flee.
Nardole arrives in a commandeered shuttlecraft to rescue them. The Doctor is electrocuted by a Cyberman, but is saved by Bill. They evacuate to a higher level of the ship containing a
solar farm populated by children and a few adults. The Doctor recovers, but suppresses the early signs of
regeneration. Bill initially remains unaware of her transformation, her strong mind acting like a perception filter, until one of the children inadvertently reveals the truth to her. Bill sheds a tear, which the Doctor calls a hopeful sign. Missy and the Master discover a camouflaged lift. They call for it, but an upgraded Cyberman arrives, which the group destroys. The Doctor warns that the
time dilation affords the Cybermen more time to evolve and strategize. Nardole discovers the floor directly below the solar farm contains fuel pipes. He is able to trigger controlled explosions, which are used to defeat the Cybermen's initial attack. The Doctor instructs Nardole to lead the human community to a solar farm on another floor and remain there to safeguard them. Bill stays to fight with the Doctor. Despite the Doctor's impassioned plea, Missy and the Master abandon him, intending to take the lift to the lowest level and escape in the Master's
TARDIS. Missy, however, changes her mind and stabs the Master. He retaliates by shooting her in the back with his laser screwdriver to prevent her regeneration, and leaves her to die. An army of Cybermen arrive, but are warded off by the Doctor until he falls after being shot. Surrounded, the Doctor ignites all the fuel pipes, engulfing the farm in a fireball and destroying the Cybermen. As Bill kneels beside the unconscious Doctor,
Heather appears, having found Bill through her tears. She saves Bill by transforming her into an oil entity like herself. They carry the Doctor inside his TARDIS, and Heather invites Bill to explore the universe with her, but also assures Bill that she can turn her human again if Bill desires. Bill bids a tearful farewell to the Doctor, hoping to see him again, and then leaves to travel with Heather. The TARDIS arrives in a snowy landscape and the Doctor awakens, and starts regenerating. Refusing to keep continually changing, he emerges and seemingly stops his regeneration. Within, the cloister bell sounds an alarm as the Doctor encounters his
original incarnation.
Continuity During the final battle, the Doctor lists the various sites of his encounters with Cybermen:
Mondas (
The Tenth Planet),
Telos (
The Tomb of the Cybermen), Planet 14 (
The Invasion), Voga (
Revenge of the Cybermen), Canary Wharf ("
Army of Ghosts" / "
Doomsday"), and the Moon (
The Moonbase). He also mentions Marinus, a reference to the events of
Grant Morrison's
Sixth Doctor comic
The World Shapers, in which that planet's
Voord evolve into Cybermen (though that story also suggests that Mondas, Planet 14, and Marinus are all the same planet). Missy mentions that the Doctor once died in a fall, referring to events in
Logopolis (1981), in which one of her previous incarnations causes the
Fourth Doctor to fall from a radio telescope tower. The First Doctor's dialogue "You may be
a doctor, but I am
the Doctor. The original, you might say" references lines spoken by the Fourth Doctor to
Harry Sullivan in
Robot, and by the First Doctor to
Tegan Jovanka in
The Five Doctors. == Production ==