A whodunit is a mystery story that keeps the criminal's identity a secret until the very end. A well-written whodunit can keep you up late turning pages, eager for the ending to be revealed.

If a book, play, or movie is a whodunit, there's usually a detective investigating what's almost always a murder case. The key to the plot, which is generally complex and confusing, is the question implicit in the informal whodunit: "Who (has) done it?" Since it was coined around 1930 in the U.S., this term has been common for a particular type of mystery or detective story.

Definitions of whodunit

n a story about a crime (usually murder) presented as a novel or play or movie

mystery, mystery story
detective story
a narrative about someone who investigates crimes and obtains evidence leading to their resolution
murder mystery
a narrative about a murder and how the murderer is discovered
Type of:
a piece of fiction that narrates a chain of related events

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