A highwayman known as The Knightmare is terrorising England in 1651. And one person who gets caught up in a stage coach raid is The Doctor, who’s arrived at this time because he’s on the trail of an alien artefact.



It’s during the robbery the Time Lord discovers The Knightmare is actually his old friend, Ashildr, in disguise. She’s the Viking girl he saved in last week’s episode by making her ‘functionally immortal’.



Now, seven centuries later she fills in The Doctor on her long eventful existence since he brought her back to life in the 9th century…



Ashildr has witnessed so much and lost so much and been through so much trauma it’s really changed her as a person. She seems very bitter.



Soon Doctor and The Knightmare, aka Ashildr, decide to team up to find the all-important artefact together. But what the Doctor doesn’t yet know is Ashildr has a secret sidekick to help her – a firebreathing monster called Leandro, who has some clandestine plans that put the world in danger…



As the Doctor and Ashildr go on their quest for the artefact, they also run into another highwayman calling himself Sam Swift The Quick (played by comedian Rufus Hound), who hates his rival The Knightmare, and there’s a big showdown between them…