People are dying mysteriously and gruesomely, and nobody has a clue what the cause is. Only health worker Mike Brady has a possible solution, but his theory of killer slugs is laughed at by the authorities. Only when the body count begins to rise and a slug expert from England begins snooping around does it begin to look like Mike had the right idea after all.
| Writing | José Antonio Escrivá | Writer |
| Crew | Basilio Cortijo | Special Effects |
| Directing | Juan Piquer Simón | Director |
| Writing | Shaun Hutson | Novel |
| Production | Juan Piquer Simón | Producer |
| Writing | Ron Gantman | Screenplay |
| Production | Francesca DeLaurentiis | Producer |
| Editing | Antonio Gimeno | Editor |
| Production | José Antonio Escrivá | Producer |
| Camera | Julio Bragado Darman | Director of Photography |
| Writing | Juan Piquer Simón | Writer |
| Production | Bill Williams | Casting |
| Editing | Richard E. Rabjohn | Editor |
| Directing | Francesca Escriva | Script Supervisor |
| Lighting | Steve Nitzberg | Gaffer |
| Crew | Patrick Tantalo | Special Effects Coordinator |
| Crew | Juan Mariné | Second Unit Cinematographer |
| Lighting | Casimiro Dengra | Gaffer |
| Sound | Luis Castro | Foley |
| Directing | Francesca DeLaurentiis | Script Supervisor |
| Costume & Make-Up | Manu Moreno | Hairstylist |
| Production | Gustavo Casado | Casting |
| Costume & Make-Up | Pilar Tavera | Seamstress |
| Costume & Make-Up | María Eugenia Escrivá | Costume Design |
| Visual Effects | Carlo De Marchis | Special Effects Supervisor |
| Crew | Kari Christensen | Property Master |
| Art | Gonzalo Gonzalo | Art Direction |
| Sound | Enrique Molinero | Sound Re-Recording Mixer |
| Camera | Carlos Bustamante | Still Photographer |
| Camera | Mark Foggetti | Camera Operator |
| Sound | Tim Souster | Music |
