Jönssonligan & den svarta diamanten

In this film, Sickan, the leader of the Jönsson gang, finds himself in a mental institution. He is attended by Dr. M.A. Busé, who becomes intrigued by Sickan's handbook on crime. When Dr. Busé is blackmailed by the banker Wall-Enberg, he teams up with Sickan's partners, Vanheden and Dynamite-Harry, to execute a daring plan. Their goal is to steal the valuable Black Diamond of the Romanovs from the National Museum.

The film cleverly combines comedic situations with a classic heist narrative, making it an entertaining watch for fans of both genres. With a strong cast including Ulf Brunnberg and Björn Gustafson, the film carries the signature style of the Jönsson Gang series.