Set up the board, place all suspect, weapon, and room cards separately, and choose a player token.
Remove one suspect card, one weapon card, and one room card at random and place them in the case file envelope.
Shuffle the remaining cards together and deal them evenly to all players.
Place all player tokens in their starting spots on the board.
On your turn, roll the die and move your token through hallways or rooms.
Enter a room to make a suggestion about the suspect, weapon, and room.
Move the suggested suspect and weapon into the room if they are not already there.
The player to your left must show you one matching card if they have one.
If that player cannot, the next player to the left must show one matching card, and so on.
If no one can disprove the suggestion, keep that information in mind.
Use secret passages, if available, to move between certain rooms.
Make an accusation when you think you know the exact suspect, weapon, and room in the case file.
Check the case file secretly.
If the accusation is correct, you win.
If the accusation is wrong, you are out of the game and can no longer take turns.
Continue playing until someone makes a correct accusation.