John Dickson Carr was an American author of detective stories, who also published using the pseudonyms Carter Dickson, Carr Dickson, and Roger Fairbairn.

The "locked-room" or "impossible crime" mystery is a type of crime seen in crime and detective fiction. The crime in question, typically murder, is committed in circumstances under which it appeared impossible for the perpetrator to enter the crime scene, commit the crime, and leave undetected. The crime in question typically involves a situation whereby an intruder could not have left; for example the original literal "locked room": a murder victim found in a windowless room locked from the inside at the time of discovery. Following other conventions of classic detective fiction, the reader is normally presented with the puzzle and all of the clues, and is encouraged to solve the mystery before the solution is revealed in a dramatic climax.