It's sort of like a murder mystery dinner, if you're familiar with those.
There are about 3 sessions during the cruise where participants meet in the WD theater and the actors discuss the situation, setting the scene, giving you a lot of clues about what/who is happening. Your job is to figure out who did the dasterdly deed by the last session when all is revealed.
It's fun....it's another activity commonly done on longer cruises.