The marquis Galeazzo di Torre Alta is murdered by a mysterious killer who calls himself Diabolicus. His heirs are his three brothers and a sister, but all of them, with the exception of Monsignor Antonino di Torre Alta, are killed by Diabolicus. The police are unable to solve the case, but when Antonino gives his inheritance to Pasquale Bonocore, illegitimate son of his father and Pasquale is in prison and therefore can't be the killer, all the clues are in the hand of the police.
Unfortunately the movie Totò diabolicus is not yet available on HBO Max.
| Directing | Steno | Director |
| Writing | Vittorio Metz | Story |
| Writing | Roberto Gianviti | Story |
| Writing | Vittorio Metz | Screenplay |
| Writing | Roberto Gianviti | Screenplay |
| Writing | Marcello Fondato | Screenplay |
| Writing | Bruno Corbucci | Screenplay |
| Writing | Giovanni Grimaldi | Screenplay |
| Directing | Mariano Laurenti | First Assistant Director |
| Directing | Mario Castellani | Second Assistant Director |
| Directing | Renata Clerici | Script Supervisor |
| Art | Giorgio Giovannini | Production Design |
| Camera | Stelvio Massi | Camera Operator |
| Camera | Renato Fait | Assistant Camera |
| Sound | Enzo Silvestri | Sound |
| Editing | Marcella Bevilacqua | Assistant Editor |
| Editing | Giuliana Attenni | Editor |
| Art | Brunello Serena Ulloa | Set Decoration |
| Costume & Make-Up | Giuliano Papi | Costume Design |
| Costume & Make-Up | Sergio Angeloni | Makeup Artist |
| Costume & Make-Up | Maria Miccinilli | Hairstylist |
| Camera | Enzo Barboni | Director of Photography |
| Production | Gianni Buffardi | Producer |
| Production | Egidio Quarantotto | Unit Manager |
| Production | Giancarlo Sambucini | Unit Manager |
| Production | Franco Pranteda | Production Secretary |
| Sound | Piero Piccioni | Original Music Composer |