Benito Freire, a pedlar in a small village in northern Spain suffers from epileptic seizures and rumours start to spread that he may be a werewolf and responsible for a series of killings. The local Abbot is called upon to form a team to investigate, in an effort to halt the harrowing murders.
| Directing | Pedro Olea | Director |
| Writing | Juan Antonio Porto | Writer |
| Editing | José Antonio Rojo | Editor |
| Production | Pedro Olea | Producer |
| Writing | Pedro Olea | Writer |
| Writing | Carlos Martínez-Barbeito | Novel |
| Camera | Aurelio G. Larraya | Director of Photography |
| Sound | Antonio Pérez Olea | Original Music Composer |
| Art | Pablo Runyan | Set Decoration |
| Costume & Make-Up | Mercedes Guillot | Hairstylist |
| Costume & Make-Up | Emilio Puyol | Makeup Artist |
| Production | Francisco Colombo | Production Manager |
| Directing | Federico Canudas | Assistant Director |
| Art | José Sánchez | Property Master |
| Sound | Luis Castro | Sound Effects |
| Sound | Eduardo Fernández | Sound Engineer |
| Lighting | Casimiro Dengra | Electrician |
| Camera | Luis E. Ibáñez | Still Photographer |
| Camera | Nicolás Redondo | Assistant Camera |
| Camera | Diego Úbeda | Camera Operator |
| Costume & Make-Up | Lola Marquerie | Wardrobe Master |
| Editing | Eduardo Biurrun | Assistant Editor |
| Directing | María Teresa Font | Script Supervisor |
| Production | Juan Casado | Production Assistant |
