Lorenzo Brandoni, an experienced detective, loses his family in an accident. He is a lonely man and is investigating a series of crimes of impossible logical solution. Nothing seems to have a logical meaning. Greater is her confusion when a young nun, Caterina, introduces herself to the detective to confess that she believes she is the murderer behind all the crimes. Lorenzo will have to investigate and surpass his deepest fears to reach the crude truth and solve the impossible crimes.