At age 12, Lasse is a tough guy and a bright one. His life is changed when his mother, pregnant at the time, abandons his beloved father. She takes Lasse with her to live with her new paramour, a dentist as authoritarian as Lasse's Elvis Presley-fan butcher dad was easy-going. The dentist has a daughter, too, and she is a jealous schemer. Lasse tries hard to conform, but can a tiger change its stripes?

A famous industrialist is murdered at a restaurant in Malmoe. Police inspector Martin Beck in Stockholm gets the case. The suspects lead to people involved in illegal arms deals. But who was the biggest criminal, the murderer or the industrialist?