Doctor: Peter Capaldi (Twelfth Doctor)
Pearl Mackie (Bill Potts)
Matt Lucas (Nardole)
Togo Igawa – Secretary-General
Nigel Hastings – The Commander
Eben Young – Col Don Brabbit
Rachel Denning – Erica
Tony Gardner – Douglas
Andrew Bryon – Ilya
Daphne Cheung – Xiaolian
Jamie Hill – Monks
Tim Bentinck – Voice of the Monks
Ronke Adekoluejo – Penny (uncredited)
Directed by Daniel Nettheim
Written by Peter Harness and Steven Moffat
Produced by Peter Bennett
Executive producer(s) Steven Moffat
Incidental music composer Murray Gold
Series Series 10
Length 46 minutes
Originally broadcast 27 May 2017
A five-thousand year old pyramid appears overnight in a disputed area of Turmezistan between American, Russian, and Chinese forces. The Secretary-General of the United Nations recruits the Doctor, as President of Earth, to help. The Doctor is still blind ("Oxygen"), a secret he is keeping from Bill.
The Monks who occupy the pyramid cause every clock in the world to display a time counting down to midnight in the manner of the Doomsday Clock. The Doctor has the military leaders use coordinated attacks on the Monks, as a show of strength, but the Monks easily deflect them. The Doctor, Bill, and Nardole soon join the leaders as they negotiate with the Monks. Using the computer running their simulations ("Extremis"), the Monks show that the Earth will become lifeless within a year. They offer humanity their help to stop a pending cataclysmic disaster, but only if they "consent". The Doctor warns that this consent would have unknown but everlasting consequences. The Secretary-General offers his consent, but the Monks disintegrate him, saying he gave it out of fear, not "love".
The Doctor realises the Monks are misdirecting them to believe a military disaster is imminent, and instead suspects the threat is biological. He and Nardole find several laboratories performing bacterial work and briefly override their internal camera systems to determine which one the Monks are watching. Bill stays behind as the Doctor and Nardole travel in the TARDIS to the lab.
Through a series of inconsequential events, two scientists have accidentally created a super-bacterium capable of breaking down all living organisms, and it is about to be vented into the atmosphere. The TARDIS arrives, but the Doctor sends Nardole back for his safety, unaware that he has been contaminated. Inside the TARDIS, Nardole collapses unconscious. Meanwhile, Bill, in communication with the Doctor, joins the military leaders as they offer to surrender. The Monks still disintegrate them, considering it a strategic move. The Doctor, with the help of Erica, one of the scientists, crafts a makeshift bomb to sterilise the bacteria and destroy the lab. However, he becomes trapped inside, unable to see a combination lock to free himself or use his sonic screwdriver on it, and he cannot get Nardole's assistance. He is forced to admit to Bill he is blind.
Bill, representing the Doctor's authority, offers her consent to the Monks, insisting they restore the Doctor's sight. The Monks accept, as this consent came from her love for the Doctor. The Doctor regains his vision and escapes the lab, while the Monks assert their control of Earth.