Six days after her disappearance, 10-year-old Helén's mangled body is found, raped and strangled. Detective Pelle Åkesson can see that the investigation is starting to drift dangerously off track under Chief Krister Berg's leadership.

Pelle is worried that Helén's case has stalled, when the body of Sofia Jansson is found. Volunteers patrol the streets, including Bengt Karlsson. Pelle and his team interrogate suspects, but power struggles take their toll on the investigation.

In an attempt to move the investigation forward, the police start to look into the murder of Jannica Ekblad, a prostitute who may have come into contact with the same man who killed Helén. A new is suspect named, a man named Grisen.

Pelle secretly reviews Helén Nilsson's case, and he finds a suspect that bears closer scrutiny. Leif Storm lived next door to Helén when she was murdered and was seen at the discount store an hour before Helén went missing.

Pelle has gone against Berg's orders and secretly sent DNA taken from Helén's body to a lab in Birmingham, England. After waiting in tense anticipation, the results arrive - the killer's genetic profile. Now they need a DNA match.

A DNA match has identified Helén's rapist. The police tear apart the suspect's cabin and find traces of Helén and Jannica's blood. However, Pelle needs additional physical evidence, or a confession from Ulf, before the prosecutor will press charges.