From the introduction:
Each player represents one of the guests who arrived this evening.
Look over at the player sitting on your right. Their guest character is your Target, and you will get to torment them throughout the game. The player on your left will be doing the same to you.
Starting at 11:00, the game passes though 12 scenes of increasing surrealism, as the house and denizens transform in response to the guests’ evil secrets. After the 12th scene, midnight strikes and we see what each guest’s fate is.