The Vanquisher

The Doctor escapes from Swarm while taking Tecteun's Ood with her. Swarm and Azure approach her, but the Doctor quickly removes her conversion plate to prevent harm. Swarm touches her just as she is split into three copies among different locations, including the Division spacecraft and Liverpool tunnels.

On the Division spacecraft, Azure attempts to return the Doctor's missing memories using a fob watch. The Doctor refuses to look at her memories, showing resistance to her aid. Azure reveals her plan to harness the Flux to create a destructive time loop across the universe.

The Ood tries to slow down the advancing Flux, working to counteract the impending universal destruction. Despite their efforts, the Flux continues to threaten to engulf everything.

Vinder and Diane manage to disrupt the internal systems of the Passenger, an entity that seems to contain or control something critical. They then escape into an unknown environment, trying to evade their pursuers.

Yaz, Dan, Jericho, and Williamson travel through a portal back to 2021. There, they meet Kate Stewart, who is leading a resistance against the Sontaran invasion. The team strategizes to locate the final Flux event.

The Doctor bargains with Kate Stewart for Claire and Jericho's help to find the coordinates of the final Flux event. She then takes her TARDIS, departing to continue her mission.

The Doctor crashes Bel's ship into the Sontaran command base in an effort to infiltrate their defenses. She is captured after being stopped by a force field and transported onto a Sontaran ship.

Karvanista reveals that he was once a companion to the Doctor during her time in the Division. He is threatened with a poison implant in his brain if he discloses more, and the Sontarans learn of the extinct Lupari species.

The Doctor frees her copy from the Grand Serpent’s torture device and strikes him. Meanwhile, Bel attempts to use Sontaran transmissions implicating alliances with enemies as a distraction. The Doctor rescues Vinder and Diane, reactivates her shield to trap the Sontarans, and uses the Passenger to absorb the Flux.

Azure and Swarm bring the Doctor to Atropos for sacrifice to Time, but the Flux's failure to free Time leads to their destruction instead. Time then reunifies with the Doctor, warning her of her impending end.

Kate and Vinder maroon the Serpent on a small asteroid. Vinder and Karvanista decide to travel together. Dan declines a date with Diane, while the Doctor invites Dan, Yaz, and herself for further adventures.

The Doctor deposits her fob watch deep inside the TARDIS, securing her memories and preparing for her next move. The episode concludes with the team regrouping to face future challenges against the Flux.