Mark Terzi goes to Genoa to take on the case of a serial killer who calls himself "The Sphinx".
| Actor | Role |
|---|---|
 Franco GasparriCommissario Mark Terzi | Commissario Mark Terzi |
 Lee J. CobbIl commedator Benzi | Il commedator Benzi |
| NNino BenvenutiGhini | Ghini |
 Ely GalleaniAngela Frizzo | Angela Frizzo |
 Spiros FocásMorini | Morini |
 Andrea AureliGiornalista | Giornalista |
 Ida MedaFranca Frizzo | Franca Frizzo |
 Massimo GirottiIl Questore Spaini | Il Questore Spaini |
 Roberto CaporaliBernardi | Bernardi |
 Guido CelanoMario Borelli | Mario Borelli |
 Francesco D'AddaRagioniere di Ghini | Ragioniere di Ghini |
 Tom FelleghyDr. Marchi | Dr. Marchi |
| EEdoardo FlorioNot listed | Not listed |
| AArchimede MuziNot listed | Not listed |
| GGianni OttavianiJudge Guglielmi | Judge Guglielmi |
 Leonardo SeveriniColantuoni | Colantuoni |
 Margherita HorowitzMaria Clerici | Maria Clerici |
 Cesare Di VitoTommasi | Tommasi |
 Mauro VestriSports Club Director | Sports Club Director |
 Carmen RussoGirl on the yacht | Girl on the yacht |
 Renato Basso BondiniGhini's Henchman (uncredited) | Ghini's Henchman (uncredited) |