Doctor: Peter Capaldi (Twelfth Doctor)
Pearl Mackie (Bill Potts)
Matt Lucas (Nardole)
Michelle Gomez – Missy
Emma Handy – Mother
Beatrice Curnew – Group Commander
Stewart Wright – Alan
Solomon Israel – Richard
Jamie Hill – Monk
Rosie Jane – Bill's Mum
Directed by Wayne Yip
Written by Toby Whithouse
Produced by Nikki Wilson
Executive producer(s) Steven Moffat
Incidental music composer Murray Gold
Series Series 10
Length 45 minutes
Originally broadcast 3 June 2017
The Monks are rulers of the Earth, and appear to have been on Earth for millions of years, guiding human development. Bill and a few others are aware of the truth: the Monks have only been present on Earth for six months. Those who hold this view are imprisoned for "memory crimes". The Doctor appears on television praising the Monks' guidance over humanity.
Bill keeps herself grounded in reality by imagining that she is talking with her long-dead mother, based on pictures the Doctor gave her. Nardole, also aware of the truth, locates Bill and helps her to find the prison hulk where the Doctor is thought to be a captive. Inside, after a team of commandos swarm inside, the Doctor tells Bill he is cooperating willingly with the Monks, believing that humanity was doomed without their guidance. Bill becomes distraught and shoots the Doctor, who appears to begin regenerating, but quickly stops. The entire scenario is revealed to have been a test by Nardole, the Doctor and the team, to make sure Bill was not under the influence of the Monks.
At the university where the Doctor and Bill work, they enter the Vault to talk to Missy, who says she has encountered the Monks before. She confirms the Monks maintain control by broadcasting a signal containing the false history to their subjugated victims via the numerous statues they have built across Earth, enabled by a psychic link established through the person who originally gave "consent"; Missy claims she defeated them during her own encounter by killing that individual. The implication is that Bill must die as the one who gave consent on Earth.
Believing there is another solution, the Doctor, Bill, Nardole, and the commandos infiltrate the Monks' pyramid in London so that the Doctor can hijack their broadcast with his own mind to break the psychic transmission. In the central chamber, the Doctor attempts to link his mind to the controlling Monk, who after a struggle overpowers the Doctor. Bill intends to sacrifice herself, linking her own mind to the Monks', despite the Doctor's protests. The Monks unintentionally replace their broadcast with images of Bill's mother, which the Doctor recognizes as a strong, loving memory in Bill's mind. Humanity recovers from the Monks' lies and rebels against them. The Doctor, Bill, and Nardole watch as the Monks abandon Earth. Sometime later, the Doctor and Bill find that most of humanity have no recollection of the Monks. In the Vault, Missy expresses remorse for those she has killed.