The Doctor and Clara, with their old friend Rigsy, find themselves in a magical alien world, hidden on a street in the heart of London.
Sheltered within are some of the most fearsome creatures of the universe… and Ashildr (Maisie Williams)! With a death sentence hanging over their heads, not all of the intruders will get out alive.
Writer: Sarah Dollard. Director: Justin Molotnikov. Producer: Nikki Wilson
Cast: Peter Capaldi and Jenna Coleman
Guest cast: Maisie Williams, Joivan Wade, Naomi Ackie, Simon Manyonda, Simon Paisley Day, Letitia Wright, Robin Soans, Angela Clerkin, Caroline Boulton, Jenny Lee.
It premieres Saturday 21 November on BBC One, with the time to be confirmed.