Four notorious bank robbers meet up in an isolated castle to divide a large number of diamonds hidden there by their deceased former boss, whose Italian wife is hosting a party.

Lucille, a paralyzed girl, is the scapegoat of her sister and her cousin Josine and Elisa. During a "game" that goes too far, they accidentally kill the lover of Elisa. Whilst attempting to make Lucille bear the guilt of the killing, they discover the frightful secret that would explain the vegetative state of Lucille.