A group of friends decide to spend a weekend in a castle belonging to Riccardo, a moody and hyper-sensitive young artist. The only other inhabitants of the castle are a mysterious housekeeper, Caterina, and the demented Aldo. The group are joined by two friends: Serena and a young American medium, Anthony. During a seance Anthony predicts a tragedy, then leaves the castle, shocked by his own visions. An hour later, Serena is found strangled to death in bed. The others become gradually more...