Parts: 1 (50-minute)
Writer: Chris Chibnall
Airdate: 31 October 2021
Production Code: n/a

Doctors: thirteenth
Companions: Yaz, Dan

Megalomaniac of the Week: Ravagers
Creature Feature: Weeping Angels, Sontarans

Story: Across time and space, disparate events are being drawn together by the inadvertent release of an alien criminal from the dawn of the universe, named Swarm. Concurrently with Swarm's prison break, a force called the Flux has begun to spread through the universe, devouring entire star systems.

Directly in its path is Earth, where down-and-out Liverpudlian Dan Lewis is enjoying Halloween evening when an aggressive alien Lupari named Karvanista — currently being pursued by the Doctor — breaks down his back door and abducts him. Why is a massive Lupari fleet headed to Earth? What has triggered the Flux, and is it connected to the TARDIS' recent malfunctions? What is Swarm's true plan, and why does he have a psychic connection to the Doctor? To answer these questions and more, the TARDIS crew will have to undertake an epic adventure...