Barcelona, Spain. A young man is murdered in the middle of the street in front of the police headquarters. Miguel and Marcial, two agents of the Criminal Brigade in charge of the investigation, find in the victim's room a newspaper where a cryptic classified ad appears.
| Directing | Jesús Castro Blanco | Assistant Director |
| Editing | Antonio Isasi-Isasmendi | Editor |
| Editing | Pascual Bibian | Assistant Editor |
| Sound | Ramón Ferrés | Original Music Composer |
| Production | Miguel Grau | Production Director |
| Writing | Julio Coll | Screenplay |
| Camera | José Luis Pérez de Rozas | Still Photographer |
| Writing | Antonio Isasi-Isasmendi | Screenstory |
| Camera | Federico G. Larraya | Director of Photography |
| Writing | Julio Coll | Screenstory |
| Costume & Make-Up | Práxedes Martínez | Makeup Artist |
| Production | Josep Maria Forn | Production Secretary |
| Writing | Antonio Isasi-Isasmendi | Screenplay |
| Costume & Make-Up | Antonio Turell | Makeup Artist |
| Costume & Make-Up | Pilar Campanales | Hairstylist |
| Directing | Francisco Pérez Riba | Assistant Director |
| Camera | Mario Bistagne | Camera Operator |
| Directing | Julio Salvador | Director |
| Writing | Julio Coll | Dialogue |
| Writing | Antonio Isasi-Isasmendi | Dialogue |
