The Unicorn Murders

infobox Book |
name = The Unicorn Murders
title_orig =
translator =


image_caption = | author = John Dickson Carr writing as "Carter Dickson"
cover_artist =
country = United Kingdom
language = English
series = Henry Merrivale
genre = Mystery, Detective, Novel
publisher = Morrow (US, 1935) Heinemann (UK, 1936)
release_date = 1935
media_type = Print (Hardback & Paperback)
pages = 240 (Dell mapback #16, 1940)
isbn =
preceded_by = The Red Widow Murders
followed_by = The Punch and Judy Murders

"The Unicorn Murders" is a mystery novel by the American writer John Dickson Carr (1906-1977), who published it under the name of Carter Dickson. It is a locked room mystery (more precisely, it is a subset of that group, an impossible mystery) and features his series detective, Sir Henry Merrivale.

Plot summary

Kenwood Blake is with the British Secret Service and romantically involved with another agent, Evelyn Cheyne. Together with Sir Henry Merrivale, they become embroiled in a battle between Flamande, the most picturesque criminal in France, and his arch-enemy Gaston Gasquet of the Sûreté. Both Flamande and Gasquet are masters of disguise, and no one knows what either man looks like. Blake, Merrivale and an assorted group of strangers are in an airplane that is forced to land near the Château de l'Ile, where the Comte d'Andrieu is apparently expecting visitors and offers them all his hospitality. One of the plane's passengers is soon found with a hole in his forehead, as if he had been gored by a unicorn, and the area was under observation by impartial witnesses such that it seems impossible for anyone to have committed the murder. Sir Henry must sort out the twin problems of who's really who and whodunnit.