The Doctor (Jodie Whittaker) and her friends Graham (Bradley Walsh), Ryan (Tosin Cole), and Yasmin (Mandip Gill), travel to Lancashire in 1612. At a village near Pendle Hall, they find an old woman being dunked because she is thought to be a witch. The Doctor tries to save her but fails. The Doctor pretends to be the Witchfinder General and fools the Magistrate Becka Savage (Siobhan Finnerman). King James himself (Alan Cumming) arrives and immediately assumes the Doctor is Graham’s assistant. Yasmin discovers the old woman being buried by her granddaughter Wiolla Twiston (Tilly Steele), who is Becka’s cousin. The Doctor saves her from a living tendril of mud and when recent victims begin to re-animate, realizes that the cause of the witch-scare is alien in nature.
While the others follow the now living corpses, the Doctor is accused of witchcraft when she confronts Becka about hiding something. She attempts to reason with King James but is dunked and escapes her bonds underwater, but she had noticed that Becka could not bear touching the tree used to dunk her. As the reanimated advance, Becka reveals that she was infected by an alien entity while chopping down the tree. She started the witch trials in hopes of finding a cure.
The alien takes over Becka’s body and speaks through her. She is the Queen of the Morax. The tree that Becka cut down was an alien prison for criminals from Morax, but it is now dysfunctional. The escaped Morax want their King to possess King James so they can conquer Earth. The Doctor uses parts of the tree to save James and restore the prison. The other Morax are forced out of their host bodies, but the Queen refuses to leave Becka. James kills them both. The next day, James tells the Doctor that all the records of the incident will be erased. And then he and Willa watch in astonishment as the TARDIS dematerializes.
The episode was written by Joy Wilkinson and directed by Sallie Aprahamian, and reception was generally positive, with particular attention to Alan Cumming’s arch take on King James. It was filmed in Wales, in Gosport, England, and in the 17th Century Living Museum of Little Woodham.
The Doctor says that a brilliant man once said that any sufficiently advanced technology is indistinguishable from magic. This of course was said by Arthur C. Clarke, which was also quoted by the Seventh Doctor, his companion Ace, Captain Jack Harkness in Torchwood, and the Twelfth Doctor. Graham kind of quotes Quentin Tarantino. King James mentions that his mother Mary Queen of Scots killed his father, which is believed by some historians.
The word Satan is spoken 39 times during the episode. The Order of the Garter dates from 1348 and James received his in 1590. Witchfinder General was a movie starring Vincent Price in 1968. This story is sort of a parody of that, but they are really nothing alike. Price had wanted to star in an American adaptation of Doctor Who, but nothing came of it.