refers to a mystery/detective film Example: The major or lead character in a whodunit is a crime-solving detective, such as in the Sherlock Holmes series of films

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

A whodunit or whodunnit (for "Who done it?" and sometimes referred to as a Golden Age Mystery novel) is a complex, plot-driven variety of the detective story in which the puzzle is paramount. The reader is provided with clues from which the identity of the perpetrator of the crime may be deduced before the solution is revealed in the final pages of the book. The investigation is usually conducted by an eccentric amateur or semi-professional detective.

None of the kids that live in your house.