"The Unicorn and the Wasp" is the seventh episode of the fourth series of the revived British science fiction television series Doctor Who, which was aired by BBC One on 17 May 2008 at 19:00. Perhaps due to its later broadcast, it received an overnight audience rating of 7.7 million, making it the most successful episode in this series since "The Fires of Pompeii". The episode is a pseudohistorical story set in 1926, in a manor owned by a character named Lady Eddison, which crime fiction novelist Agatha Christie is visiting, and is a comedic episode with a murder-mystery storyline.