The series introduces Pearl Mackie as Bill Potts, and also features Matt Lucas as Nardole. Michelle Gomez and John Simm return as their respective incarnations of the Master. The main story arc for the first half of the series revolves around the Doctor and Nardole occupying themselves at a university while they guard an underground vault containing Missy. Missy later travels with the team in the TARDIS, and eventually partners with her previous incarnation as they battle a Cyberman onslaught.
Two worlds collide when the Doctor meets Bill. A chance encounter with a girl with a star in her eye leads to a terrifying chase across time and space. Bill’s mind is opened to a universe that is bigger and more exciting than she could possibly have imagined – but who is the Doctor, and what is his secret mission with Nardole on Earth?
The language of the future is emoji! The Doctor takes Bill to a spectacular city on a distant planet - but where are the colonists? A band of 'cute' droids hold the deadly answer.
London, 1814. The entire city has turned out for the biggest Frost Fair in decades. But beneath the frozen Thames, revellers are disappearing, snatched through the ice and pulled into the depths where a terrifying monster lurks. Will the Doctor and Bill stop the slaughter before they too are dragged into the icy waters?
Why do floorboards creak? When a sinister landlord shows Bill and her friends the perfect houseshare, they have no idea what lies ahead... knock knock, who's there?
“Space - the final frontier. Final because it wants to kill us.” Trapped on a space station with no oxygen, the Doctor, Bill and Nardole are horrified to discover the automated spacesuits keeping them alive are also trying to kill them!
“The Veritas. The truth. Truth so true you can't live with it. Is that looking into hell... or seeing the light?” Everyone who has ever read the Veritas has been found dead. In a forbidden library at the heart of the Vatican, the pope urges the Doctor to read the ancient text - but can he handle the truth?
An “ancient” pyramid appears overnight. Every clock in the world begins counting down to the Earth's destruction. Three opposing armies lie ready to annihilate each other. An alien race stands ready to offer humanity a deal that could save them, but also enslave them. It's a terrifying race against time to save the world. Will the Doctor be forced to accept their help?
Earth has been invaded and Bill is living alone, an isolated figure surviving in occupied Britain. The Doctor is imprisoned and appears to be on the side of the enemy, flooding the airwaves with fake news. Bill and Nardole must embark on a deadly mission to rescue the Doctor and lead the resistance against the new regime, whatever the cost.
“God save the Queen” has been scrawled on the surface of Mars. What are Victorians doing on the home of the Ice Warriors? And what will they find beneath the Martian soil?
A long time ago, the ninth legion of the Roman army vanished into the mists of Scotland. Bill has a theory about what happened, and the Doctor has a time machine. But when they arrive in ancient Aberdeenshire, what they find is a far greater threat than any army. In a cairn, on a hillside, is a doorway leading to the end of the world.
Friendship drives the Doctor into the rashest decision of his life. Trapped on a giant spaceship, caught in the event horizon of a black hole, he witnesses the death of someone he is pledged to protect. Is there any way he can redeem his mistake? Are events already out of control? For once, time is the Time Lord’s enemy.