Captured by Vikings, The Doctor and Clara must help protect their village from Space Warriors from the future, the Mire. Outnumbered and outgunned their fate seems inevitable. So why is The Doctor preoccupied with a single Viking girl?
Deadly highwayman 'the Nightmare' and his sidekick stalk the dark streets of London. However when they find loot that is not of this world, they come face-to-face with The Doctor.
The Doctor and Clara, with their old friend Rigsy, find themselves in a magical alien world, hidden on the street in the heart of London. Sheltered within are some of the most fearsome creatures of the universe, and Ashildr.