DRAMA An arresting prologue introduces us to an altered, present-day Earth. One with a rewritten human history, and in which those cowled corpses the Monks are now our benefactors. And where the Doctor is behaving very creepiily indeed.

In this new world order deniers are imprisoned and Bill, who can see through the deception, is struggling to keep shtum. She even talks to her dead mother in a bid to stay sane.

It's no bad idea to rewatch the end of the previous episode first to grasp why we are in this dystopian hell. Toby Whithouse's intense and twisty tale is a fine example of emo-Who, thanks to Pearl Mackie's involving performance as Bill, going through untold agonies. Some of the unease is deflected by the cute comic timing of Matt Lucas as Nardole, and by some lovely lines of dialogue from Whithouse. And, finally, we see the Doctor open that mysterious Vault...