A dead and unknown woman is found in a canal. Police inspector Martin Beck becomes involved in the case. After several months the woman is identified. The police reconstruct the woman's last trip on the canal boat "Wilhelm Tham".

The police lieutenant Nyman is murdered in his hospital bed and Martin Beck and his colleagues have another murder to solve. They discover that Nyman was a very brutal and tough policemen who got many complaints about police-brutality. Particularly interesting is Åke Eriksson, whose wife died in police custody because of Nyman. Eriksson climbs up on a roof in central Stockholm and starts to shoot at people on the street below...

A routine mission ends up in a flaming inferno when a house suddenly explodes. It looks like a spectacular suicide attempt but the technical investigation reveals unexpected evidence. Beck and his men are soon on the tracks of a narcotic syndicate...

The unidentified dead body of a young woman is found in Göta kanal, Sweden's longest canal. At first there seem to be no clues to what happened, but thorough research by criminal inspector Martin Beck and his colleagues reveal that she is a librarian from Nebraska, USA. Helped by amateur footage from a cruising ship, they find a likely suspect but still need more evidence before they can arrest him.

A serial-killer attacks and murders little 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.

A woman is found murdered in a closed amusement park. A young couple who happen to be there at the same time become, without their knowledge, suspects for the murder. They are chased by a large number of police but only Martin Beck believes them to be innocent.

The gardener decides to avenge the death of his mentally disturbed wife by killing the men he considers responsible. One of them is a pop star that takes part in great marathon race in Stockholm. While the killer methodically prepares and patiently waits his victim, Inspector Beck and his men must determine the exact location of the shooting on 42 kilometers of path before it's too late.