From the introduction:
This is a game for three or four players. Two will be suspects accused of some serious crime, and one or two will be police detectives. It’ll be most fun with two and two. Cut out the cards below and hand them out.
This game operates on the principle of agreement – when someone articulates some fact about the crime, the suspects, or the overall situation, you must accept and build on that fact.
The game ends after twenty minutes or when the detectives are satisfied they’ve got as much as they are going to get out of the suspects.