Sickan, Vanheden and Rocky try to rob the Berns nightclub one night, but Vanheden has made the mistake to invite his constantly drunk cousin, the old dynamiter Dynamite-Harry and he ruins the plan. Sickan is arrested, and has to spend 10 months in a small, locked room. When he is released, he has a new plan, but Rocky and Vanheden have decided to go straight. Together with Dynamite-Harry, Sickan plans to rob a cold store, managed by their arch-enemy, Wall-Enberg.
The movie begins with the Jönsson gang making a minor burglary. It goes wrong and the gang leader, Sickan, gets caught. After he has spent 10 months in jail, Vanheden and Rocky come to welcome him when he's released. But he doesn't take notice of them, and he's picked up by the mysterious banker Wall-Enberg Jr. instead. He wants Sickan to perform a burglary in Switzerland, in order to retrieve the famous Bedford Diamonds. Sickan does this but is fooled by Wall-Enberg and nearly gets caught. When he returns to Sweden and re-unites with his old gang members, he's set on revenge, both physically and psychologically...
As always, Sickan has come up with a new plan. This time he wants to rob the IKEA furniture store. During their nightly break-in Sickan discovers that the store is used as a secret smuggling central for sending American computers to the Soviet Union. The computers are picked up by Soviet submarines sneaking into the Swedish archipelago. Naturally, it is their arch enemy Wall-Enberg who is behind all of this.
