With the younger crowd, it might be fun to bring the mystery into the modern day. Stage it so it appears the mystery is taking place at a successful record producer?s home. Assign relevant guests profiles such as Mega Rock Star, Back up Dancer, Famous Teen Actress and so on. Include detailed character facts like?teen actress just had ugly break-up with mega rock star.
Let guests know their character before the event so they have time to dress according to their character description. Or, have a table full of costume props such as feather boas, dark sunglasses, costume jewelry, wigs, etc. and let them get in to character. This will bring a lot of fun and hilarious moments.
I love the idea of a ghost guide helping guests solve the mystery. Consider having an unseen ghost do the same. Hide a walkie talkie in one or more of the rooms. Someone can stay behind the scenes and give the creepy clues to unsuspecting clue gatherers. Or you can write clues with ghost ink pens that show under certain lighting. Or, use glow-in-the-dark pens.
Oh, and of course, use white tape to outline a body on the floor. This brings a touch of realism that will get guests to talking. Have each person lay down in the outline of the body for a photo. Print out on computer and hand out at end of evening. Or, just e-mail the momento at the end of the night.