1935. The air is already poisoned with anticipation of the coming war. But near Prague, in a medieval castle, sleeps an evil no less terrifying. It holds the “devil’s six”—killers who have gained fame for their cruelty. A young psychiatrist, a student of the legendary C. Jung—Victor Kosarek—arrives at the clinic hoping to uncover the nature of evil and to find in these patients the “aspect of the devil.” Meanwhile, Prague is rocked by a string of brutal murders committed by a maniac known as the Leather Apron. Victor tries to connect these murders with the dark secrets of his patients. But maybe the devil himself is involved here…