Sickan, the leader of the criminal Jönsson gang is incarcerated in a mental institution, attended by Dr M.A. Busé, who admire a handbook in crime that Sickan has been writing. Blackmailed by the nefarious banker Wall-Enberg, Dr Busé and Sickan's partners Vanheden and Dynamite-Harry execute Sickan's plan of stealing the valuable Black Diamond of the Romanovs from the National Museum.
Producer: Ingemar Ejve, Katinka Faragó
Writer: Hans Åke Gabrielsson, Rolf Börjlind
Director: Hans Åke Gabrielsson
Director of Photography: Rolf Lindström, Lars Karlsson
Ragnar Vanheden
Dynamit-Harry
Dr. Max Adrian Busé
Doris
Lillis
Lohman
Andersson
The Chief of Police