A thriller taking place during Season 21 which sees the Doctor and Turlough land in 18th century London, where someone is terrorising the higher echelons of society using apparently paranormal means. 

What is the secret of the screaming walls? Why are the patrons of the Diablo Club disappearing after losing at cards to the charming Sir Nikolas Valentine? And what is the connection with the charming highwayman Lovemore?