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.