PART 1: The Doctor (Peter Capaldi, in his final series) has taken an oath to guard the contents of a mysterious vault when he meets eager-to-learn Bill Potts (Pearl Mackie). The Time Lord is desperate to show his new friend the wonders of the universe and it falls to loveable android Nardole (Matt Lucas) to remind him of his duty. From emoji-speaking robots to a monster beneath the Thames, Bill's universe is about to get a whole lot bigger.
PART 2: The Doctor continues his journey through Time and Space, and with Bill and Nardole he embarks on a further set of exhilarating adventures. Their travels land them face-to-face with Ice Warriors and Cybermen, but the threesome's adventures draw to a terrifying conclusion as a long lost face returns from the past.