The Doctor joins forces with an investigative journalist and a superhero to save New York from a deadly alien threat.

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?

In the far future, at the edge of the galaxy, there is a gleaming, perfect city. This brand new human settlement is said to hold the secret of human happiness - but the only smiles the Doctor and Bill can find are on a pile of grinning skulls.

Something is alive in the walls, and the emojibots are watching from the shadows, as the Doctor and Bill trying to unravel a terrifying mystery.

The Tardis lands in Regency-era London, where the Doctor and Bill attend the last of the great frost fairs. However, sinister forces are afoot, and something is stirring under the frozen surface of the River Thames. When people begin to mysteriously vanish while on the ice, the Time Lord and his new friend are drawn into another investigation. Bill discovers the England of the past is more like the modern day than she expected, and begins to realise that not all monsters come from outer space.

Bill and some of her friends decide to move in together, and find what seems to be the perfect house. However, the absurdly cheap rent, and a decidedly creepy landlord suggest that domestic bliss might not yet be on the cards. The Doctor believes something is seriously wrong with his assistant's new home, plagued as it is with strange drafts and oddly creaky floorboards, and that's without considering the ominous tower found at the very heart of the building - one that doesn't seem to have an entrance.

The Tardis picks up a distress call from deep space, but when the Doctor, Bill and Nardole try to answer it, they find themselves trapped on board the space station Chasm Forge. On further investigation, they discover all but four people on board the facility have been cuddled - but the dead are still walking. Now stranded in a future where oxygen is sold by the breath, and space-suits are valued more highly than their occupants, the time-travellers face a battle for survival against the darkest evil of all.

In the Haereticum - the Vatican's secret library of blasphemy - there is an ancient book known only as The Veritas. Throughout history, anyone who has ever read it has immediately taken their own life. Now a new translation is online, and the danger is spreading. The Vatican appeals to the Doctor. Will he read The Veritas? But can even the Doctor survive the ultimate 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 enslave them. It is 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.

The Doctor, Bill and Nardole arrive on Mars and find themselves in an impossible conflict between Ice Warriors... and Victorian soldiers. As the Martian hive awakes around them, the Doctor faces a unique dilemma - this time the humans, not the Ice Warriors are the invaders. When Earth is invading Mars, whose side is he on?.

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 passing 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.

"Without hope, without witness, without reward". The Mondasian Cybermen are on the rise. It's time for the Doctor's final battle.