The leader of the Jönsson gang, Sickan, is institutionalized and his mental institution doctor, Dr. M.A. Busé, is fascinated by Sickan's crime handbook. Forced by the corrupt banker Wall-Enberg, Dr. Busé and Sickan's accomplices, Vanheden and Dynamite-Harry, carry out Sickan's plan to steal the priceless Black Diamond of the Romanovs from the National Museum.
Jönssonligan & den svarta diamanten
A mastermind criminal, imprisoned in a mental institution, orchestrates his illegal schemes through his loyal gang and a complicit doctor.
