Martin Beck's loyalty to his colleague Gunvald Larsson is put to the test when Martin receives orders to arrest him. The origin is a burnt female corpse found at a crime scene where Gunvald is the first to arrive, subsequently taking up the hunt for the killer on his own.

Gunvald is pursued by SÄPO. The victim was an internationally wanted member of a group of environmental activists carrying out attacks worldwide. Martin Beck discovers the group plans to strike in Sweden and must work with SÄPO to prevent a catastrophe.

Why a so unbecomingly unshaven Mikael Persbrandt in a somewhat mediocre "Beck"? The film is based on Maj Sjöwall and Per Wahlöö's characters.