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.
| Camera | Rolf Lindström | Director of Photography |
| Writing | Rolf Börjlind | Writer |
| Editing | Roger Sellberg | Editor |
| Writing | Hans Åke Gabrielsson | Writer |
| Production | Katinka Faragó | Producer |
| Directing | Hans Åke Gabrielsson | Director |
| Production | Ingemar Ejve | Producer |
| Sound | Thomas Lindahl | Original Music Composer |
| Directing | Carolina Häggström | Continuity |