Op kerstavond wordt een man vermoord. Een andere man meldt zich bij de politie en wil inlichtingen verstrekken op voorwaarde dat de minnares van zijn zoon het land zal worden uitgezet. Commissaris Belli (Nero) vertrouwt het niet en volgt de man, hetgeen hem in allerlei moeilijkheden, waaronder mysterieuze vrouwen, brengt.
Nee, helaas is Un detective nog niet beschikbaar op Netflix in Nederland.
| Directing | Romolo Guerrieri | Director |
| Writing | Ludovico Dentice | Novel |
| Production | Mario Cecchi Gori | Producer |
| Sound | Fred Bongusto | Original Music Composer |
| Editing | Marcello Malvestito | Editor |
| Camera | Roberto Gerardi | Director of Photography |
| Writing | Franco Verucci | Screenplay |
| Writing | Alberto Silvestri | Screenplay |
| Sound | Robby Poitevin | Music Arranger |
| Art | Giantito Burchiellaro | Production Design |
| Directing | Renzo Genta | First Assistant Director |
| Camera | Gastone Di Giovanni | Camera Operator |
| Sound | Guido Ortenzi | Sound |
| Directing | Serena Canevari | Script Supervisor |
| Camera | Franco Bruni | Assistant Camera |
| Camera | Maurizio Maggi | Assistant Camera |
| Editing | Francesco Malvestito | Assistant Editor |
| Production | Camillo Teti | Unit Manager |
| Production | Renato Fiè | Unit Manager |
| Production | Bruno Altissimi | Administration |
| Costume & Make-Up | Mario Della Torre | Assistant Costume Designer |
| Art | Francesca Saitto | Assistant Production Design |
| Production | Antonio Barone | Production Secretary |
| Sound | Mario Morigi | Sound Mixer |
| Production | Luciano Luna | Production Manager |
| Writing | Massimo D'Avak | Screenplay |
| Costume & Make-Up | Luca Sabatelli | Costume Design |
| Costume & Make-Up | Franco Corridoni | Makeup Artist |
| Costume & Make-Up | Rosa Luciani | Hairstylist |
