Crime: A crime is committed—usually a murder

1.   The Crime as Trigger: The crime must occur reasonably early in the story.

2.   The Criminal Mastermind: The criminal must be clever enough to have hidden his identity sufficiently that it’s not obvious from the start who committed the crime.

3.   The Detective: The investigator must be clever enough to solve the crime. If he’s not a professional (cop, PI), he must have some special skill or knack that helps him uncover clues others miss.

4.   Now It’s Personal: At some point, the investigation becomes personal for the investigator.

5.   Clues & Red Herrings: The investigator finds clues, but some clues are red herrings.

6.   Accuse: The investigator uncovers/confronts/denounces the criminal.

7.   Justice Theme: The ending results in justice, injustice, or ironic justice.