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?

In the Crimean War, the Doctor discovers the British army fighting a brutal alien army of Sontarans, as Yaz and Dan are thrown deeper into a battle for survival. What is the Temple of Atropos? Who are the Mouri?

'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?