On Halloween, all across the universe, terrifying forces are stirring. The life of Dan Lewis is about to change forever. Why is the Doctor chasing Karvanista? What is the Flux?

'Time is beginning to run wild.' On a planet that shouldn’t exist, in the aftermath of apocalypse, the Doctor, Dan, Yaz and Vinder face a battle to survive.

In the final epic chapter in the story of the Flux, all hope is lost. The forces of darkness are in control. But when the monsters have won, who can you count upon to save the universe?