A WHODUNIT is a type of mystery story in which the reader is challenged to solve the crime before the detective character does. The term 'WHODUNIT' is derived from the question 'Who done it?' and is often used to describe a murder mystery. In a WHODUNIT staple, the main elements are a CORPSE, an ALIBI, and POISON. The CORPSE is the victim of the crime, the ALIBI is an excuse or explanation for why the suspect was not present at the time of the crime, and the POISON is the method used to commit the crime.