The story takes place in the 50's. A 13-year old boy, who has never seen a naked woman, collects pictures of pin up girls. One of his pictures is that of a naked blonde woman holding a guitar that is covering her private parts. One day a woman that resembles the girl in the picture moves in to the neighbourhood. Could it be the same blonde?

A serial-killer attacks and murders young girls in the parks of Stockholm. The police have trouble finding any evidence to find the killer. But when a newsstand is robbed in one of the parks while the murderer strikes again, police inspector Martin Beck believes that the robber may be an important witness. Plot by Mattias Thuresson.

Sickan, the leader of the criminal Jönsson gang is incarcerated in a mental institution, attended by Dr M.A. Busé, who admire a handbook in crime that Sickan has been writing. Blackmailed by the nefarious banker Wall-Enberg, Dr Busé and Sickan's partners Vanheden and Dynamite-Harry execute Sickan's plan of stealing the valuable Black Diamond of the Romanovs from the National Museum.

When Vanheden and Dynamit-Harry tries to break doctor Busé out of jail, they get Herman Melvin instead. He has been working at the Swedish Mint and the doctor, who has started to think like Sickan, has written a plan for making a burglary there, on Melvin's back. However, something goes wrong. They don't get a lot of Deutsch-marks as they planned but instead, they end up on a ship going to Poland, together with bunches and bunches of Polish Zlotys (the Polish currency). In Poland, they discover that the mafia are very interested in that money and Wall-Enberg is working with the mafia.