A young black girl is killed during what appears to be a voodoo ritual. Coliandro is entrusted with the task of taking care of the victim's sister, who has arrived in Bologna from Africa.

Coliandro gets involved in a bank robbery in the center of Bologna. The three robbers, young and inexperienced, are soon rendered harmless by three hostages, who, in turn, take the other people hostage.

Agent Gargiulo shows up at Coliandro's house in the middle of the night, drunk and with a bloody knife in his hand: the inspector tries to reconstruct what happened, but it doesn't seem easy.

The husband of an old Coliandro professor is killed inside the University of Bologna. The woman is accused of the murder due to the constant escapades of her husband: did she really go like this?