The Weeping Angels transport the Doctor (Jodie Whittaker) to a spaceship carrying the Head of Division—Awsok (Barbara Flynn), who orders an Ood (Simon Carew and voice of Silas Carson) to create the final Flux event. Division is travelling to another universe as a seed vault with genetic material from this universe. Awsok blames the Doctor for destroying the universe because she defected from the Division. Awsok, it seems, is really Tecteun, the Gallifreyan who found the Doctor as a child and raised her, creating the Time Lords. The Doctor blames Tecteun for her lost life. Tecteun has a fob watch containing the Doctor’s lost memories.
Dan, Yaz, and Jericho travel around the world in 1904 to find the date of the world’s end, dodging assassins all the way. A Nepalese hermit suggests they reunite with Kalvanista. They leave a message at the Great Wall of China, but he can’t time-travel to see it. They search out Joseph Williamson (Steve Oram) and his tunnels under Liverpool because he found doorways to different times and places.
In 1958, a general asks the Grand Serpent, now named Prentis (Craig Parkinson) to help form UNIT. Over the years, he will be part of UNIT’s leadership. In 2017, he shuts it down and Kate Stewart (Jemma Redgrave) threatens to expose him. An assassination attempt fails and she goes into hiding. With UNIT eliminated, in 2021 the Sontarans invade Earth.
A Lupari ship falls and Kalvanista (Craig Els) takes the missing Lupari ship stolen by Bel (Thaddea Graham), just as she catches up to the Passenger signal. The Sontarans attack Bel’s ship. Vinder (Jacob Anderson) is also after the Passenger signal and finds survivors being disintegrated by Swarm (Sam Spruell). He meets Diane (Nadia Albina). Swarm and Azure (Rochenda Sandall) arrive on the Division ship and plot revenge on Division. Swarm disintegrates Tecteun (Barbara Flynn) and turns to attack the Doctor.
The episode, Chapter Five of Flux, was written by Chris Chibnall and directed by Azhur Saleem. Jemma Redgrave returns to Doctor Who as Kate Stewart of UNIT, who was last seen in 2015, and we hear the voice of the late Nicholas Courtney, who for years played Alastair Lethbridge-Stewart, her father. The episode received excellent reviews.