Things You'll Need
Instructions
Choose a core group of characters. There should be 5 to 9 main characters who know the plot beforehand and serve as the "actors" for the rest of the guests, who will be detectives trying to figure out exactly what happened. There should be one or more victims (who are killed over the course of or even before the murder mystery story begins), a killer, potentially an accomplice and suspects.
Write an overarching plot for the core players. Create a timeline that includes which character was killed, when and by whom and where the other core characters were at the time. To make it trickier, make the other characters' alibis seem far fetched.
Create motives for each core character. There should be a reason that each one could potentially have killed the victim or victims. To make the deaths seem more dramatic and to create commotion in the room, turn out the lights for the deaths, and have the killer maneuver near the victim.
Make a timeline for the party itself, including when the "play" will start. It should begin with introducing the characters and letting the guests talk amongst themselves. After 10 minutes or so, you can have an action or clue to who could be the killer. Make the motives for each suspect clear. About 20 or 30 minutes into the party, you can have the first death, and give the "detectives" time to question the actors.
Create a dramatic ending for the party, which can include a tearful or angry confession from the killer, as well as any other elements that enhance one of the main characters (for example, a sudden confession of love).