Need design ideas for a 3 layer black mystery party cake for 18th bday

I'm sorry no onle has been able to suggest anything for you.
I'm not really understanding what a 'black mystery party' is all about.
Is there an invitation you could copy or take elements from?

we had a mystery dinner and it was for not really knowing what foods you were going to get based off the menu choices. So maybe make the cake into something not cake like like a hamburger or a non food item like a book or something. hth.

I'm not quite sure I understand the entire theme of the party. I saw this cake yesterday and think it could be mimicked to get your theme.

http://www.cakecentral.com/cake-photo_1208088.html

If there are going to be clues for the guests to solve you can replace the objects on the cake that suit your party. Maybe add some question marks...

Hope you get some other good ideas.

I was thinking of thumbprints and a big magnifying glass. Questions marks are good too.

How about making a ball pan into Sherlock Holmes hat, still could add a magnifying glass.

Each mystery party has a theme, as someones else suggested, it you can get the theme, it will give you CLUES...........

haha

Here's an idea I found..............

MYSTERY CAKE

* Bake a sheet cake; cool
* Slice the cake into individual pieces, one piece for each guest. Be sure to keep the slices together.
* Scoop out a tiny amount of cake from each slice.
* Feel the holes with small toys or mystery snack sized candy, and carefully turn the cake over.
* Cover the cake with frosting. Decorate it with question marks in all colors
* Serve the precut slices, and warn everyone that there's a mystery candy surprise inside each slice!