This episode was so full of surprises that anyone averse to spoilers should not read it. Just see it if you can.
The Doctor (Jodie Whittaker) has been looking for the Master, who probably escaped the Kasaavin realm, and her companions Graham (Bradley Walsh), Yasmin (Mandip Gill), and Ryan (Tosin Cole) are trying to get her to talk about it. She learns that a platoon of Judoon have descended on Gloucester and put a forcefield around the city while they search for a fugitive. The Doctor bypasses the forcefield and arrives in the city. Graham is teleported to a stolen spaceship by Captain Jack Harkness (John Barrowman), who thinks Graham is the Doctor.
The Judoon try to attack the apartment of Lee (Neil Stuke) and Ruth Clayton (Jo Martin), but the Doctor intervenes and stalls them long enough to question them and find a hidden box. Lee will not answer her questions but covers their escape, turning himself in to the Judoon. He is killed by Gat (Ritu Arya) because he is an associate of the fugitive they’re looking for.
The Doctor flees to Gloucester Cathedral with Ruth, while Ryan and Yaz are teleported to Captain Jack’s ship. When he finds that he cannot teleport the real Doctor because of the Judoon’s forcefield, he tells the companions to tell her to beware the lone Cyberman and not give in. He teleports the companions to Gloucester and then teleports away.
The Doctor and Ruth are surrounded by Judoon. Ruth attacks them, ripping off the commander’s horn, and forces them to retreat. She reveals that Lee sent a text before his death leading them to a lighthouse where she grew up. Under a blank gravestone nearby, the Doctor finds a TARDIS buried. Ruth enters the lighthouse and is engulfed in energy which restores her memory. She was once the Doctor, though neither of them remembers the other. Ruth seems to be an unknown past incarnation.
Her TARDIS is taken aboard the Judoon ship and both Doctors confront Gat, who is revealed to be a Time Lord searching for Ruth. Though Ruth disappears, the Doctor introduces herself and shows Gat a vision of the destroyed Gallifrey. Gat fires a sabotaged weapon and is killed. Ruth drops the Doctor off in Gloucester, where her companions pass on Captain Jack’s message. She thinks something is coming for her.
The episode was written by Vinay Patel and Chris Chibnall and directed by Nida Manzoor. It was very highly praised for its twists and turns. John Barrowman had not been seen for ten years and was not announced ahead of time. Nicholas Briggs, who has done many a voice on Doctor Who, including most of the Daleks, did the voice of the Judoon captain. The character, Pol-Kon-Don, was named for producer Paul Condon, who died in 2019. To keep his appearance a secret, Barrowman faked a house renovation in Cardiff and ended up renovating the house for real.
This is largely considered one of the best Jody Whittaker episodes and I have to agree. I love those Judoon, but they were just the beginning. More important was the promising return of Captain Jack Harkness, who had been much missed, and the startling revelation of a previously unknown incarnation of the Doctor, and all the baffling questions that arise from that revelation. Jody Whittaker herself was at the top of her game, revealing all sorts of emotional depth that had been glossed over by her frenetic, jovial style. We love their power and their brilliance, but the Doctors seem to be at their best when they don’t have all the answers.