Kayo, a young Japanese doctoral student in art history, unwittingly witnesses a ruthless execution. She accidentally encounters Coliandro, who decides to protect her and hide her in his home with his brother Kenzaburo. Kenzaburo, who came from Japan to protect his sister, is a former yakuza informer, a fearsome Japanese mafia who is hunting them.

Coliandro seems on the verge of a successful conclusion to his romantic adventure. But, just as things are going, Giacomino shows up at his house, sleepy, hungry, and handcuffed. The motive is incredible: Giacomino is accused of committing a series of brutal murders. To help his friend, Coliandro must hunt down the real serial killer.

Coliandro is forced to be Paffoni's dance partner for an evening. To escape this unpleasant task, he finds himself investigating the murder of a young singer. He's helped not only by Paffoni, a skilled dancer, but also by Natascia, the young and beautiful new singer in the liscio orchestra led by the shady Vasinto and his wife Ersilia, known as "Vagona."

At the police station, Coliandro meets Asmareth, a young and beautiful Eritrean cultural mediator who works for the police. Believing her to be an illegal immigrant, Coliandro makes one blunder after another. To gain forgiveness, he agrees to help her with an investigation she's conducting into illegal work. Coliandro and Asmareth thus expose a gang organizing "manhunts" for bored, wealthy provincials.