Jimmy Logan, a detective, tries to retrieve a diamond from the British crown stolen by the traitorous chief of the English Secret Service. After carrying out dangerous investigations at Montecarlo, Beirut and Hamburg, he discovers that the headquarters of the thieves is located in a mental hospital and sets about infiltrating their ranks.
Ray Danton
as Jimmy Logan
Agnès Spaak
as Arianne
Tiziano Cortini
as Professor Froyd
Luciana Gilli
as Desireé
Monica Pardo
as Lolita
Pamela Tudor
as Gladis
Daniele Vargas
as Dolmann
Francesco Mulè
as Gran Capo
Gioiella Minicardi
as Sheila
Seyna Seyn
as Lulu Mao
Andrea Aureli
as Schwarz
Fortunato Arena
as Brett
