Two patrolling cops stumble on to three criminals who have just stolen large amounts of explosives, and are killed in cold blood. Martin Beck and his team must now work day and night to find out who the killers are and what they are planning to do with the explosives before it's too late. Meanwhile, Gunvald Larsson who was a close friend of one of the murdered cops is ignoring all rules in his quest for revenge.

A common day in Stockholm some people face major changes. The owner of a fur shop meets an animal rights activist. A priest has restrictions on Saint Lucy's Day. An old woman evicts and a young man disappoints his father.

In 1939, a group of skiers set off on a five-day ski trip in the Lapland mountains. Due to a severe storm, they are snowed-in a mountain cabin. On the first night, a murder takes place, the successful businessman Weismann is brutally stabbed to death. The group's participants realize, horrified, that the killer must be one of them. In order to endure the following days trapped in the cabin, they must try to solve the murder mystery themselves.