William Hartnell plays Doctor Who in this episode from the British sci-fi series. The adventure begins when Doctor Who and Vicki (Maureen O'Brien) discover an unexpected passenger aboard the TARDIS: an astronaut named Steven. As the Doctor roams ancient England searching for evidence to convince the skeptical stowaway of time travel, he discovers a monastery filled with baffling modern appliances. The mystery deepens when the Doctor falls into the trap of a monk on an unusual mission.