A recent widow has invited a group of family friends to her large and secluded country home. However, what the guests don't know is that the reason they've been assembled is that their host suspects one of them might be her husband's killer and she's intent on uncovering the identity of his murderer. As the guests begin to suspect each other, revealing long-kept and sinister secrets in the process, an unknown, black-gloved killer begins bumping them off in a variety of nasty ways.
You can now watch The Killer Is One of Thirteen online on the following streaming providers in the United States.
| Writing | Javier Aguirre | Screenplay |
| Directing | Javier Aguirre | Director |
| Art | Eduardo Torre de la Fuente | Set Decoration |
| Writing | Alberto S. Insúa | Screenplay |
| Sound | Alfonso G. Santisteban | Original Music Composer |
| Editing | Petra de Nieva | Editor |
| Production | José Antonio Cascales | Executive Producer |
| Camera | Francisco Fraile | Director of Photography |
| Directing | Juan Antonio Arévalo | Assistant Director |
| Costume & Make-Up | Carlos Paradela | Makeup Artist |
