After a young man is killed in an unexplored subterranean cavern and his girlfriend driven mad by something she saw there, a track found at the scene cannot be identified with any known animal and thus a scientific expedition is launched to find out just what it is that is living there.
| Directing | Alfredo B. Crevenna | Director |
| Sound | Raúl Lavista | Music |
| Writing | José María Fernández Unsáin | Writer |
| Production | Jesús Sotomayor Martínez | Producer |
| Camera | Raúl Martínez Solares | Director of Photography |
| Editing | Carlos Savage | Editor |
| Production | Heberto Dávila Guajardo | Executive Producer |
