Na het verwerken van de dood van zijn broer Sergio, verheugt verpleger Mario zich op een nieuw hoofdstuk in zijn leven met de komst van zijn eerste kind. Maar wanneer kartelbaas Antonio Padin uit de gevangenis wordt ontslagen wordt Mario aangesteld om zorg voor hem te dragen. Al snel begint hij zich af te vragen of zijn zorgplicht belangrijker is dan de levens die deze man heeft vernietigd.
Ja! de film Quien a hierro mata is nu beschikbaar om te kijken op Netflix in Nederland.
| Art | Javier Alvariño | Art Direction |
| Art | Paula Marín | Set Decoration |
| Production | Arantza Vélez | Casting |
| Costume & Make-Up | Silvia Neira | Makeup & Hair Assistant |
| Costume & Make-Up | Erea Pérez | Makeup Artist |
| Art | Ventura Villar | Assistant Set Decoration |
| Costume & Make-Up | Susana Veira | Makeup & Hair |
| Directing | Lorena Vilas | Second Assistant Director |
| Directing | Paco Plaza | Director |
| Writing | Jorge Guerricaechevarría | Writer |
| Writing | Juan Galiñanes | Writer |
| Camera | Pablo Rosso | Director of Photography |
| Sound | Maika Makovski | Music |
| Costume & Make-Up | Vinyet Escobar | Costume Design |
| Production | Borja Pena | Producer |
| Production | Emma Lustres | Producer |
| Production | Mercedes Gamero | Producer |
| Production | Mikel Lejarza | Producer |
| Sound | Alex Alcántara | Additional Sound Re-Recording Mixer |
| Sound | Kevi Aragunde | Foley Mixer |
| Sound | Irma Areta | Sound Post Supervisor |
| Sound | Ignacio Arrojo | ADR Recordist |
| Sound | Miguel Barbosa | Foley Artist |
| Sound | Gabriel Gutiérrez | Sound Designer |
| Sound | Kevin Hortigüela | Sound Effects Editor |
| Sound | David Machado | Sound |
| Sound | Yasmina Praderas | Sound Mixer |
| Sound | Diego S. Staub | Foley Mixer |
| Directing | Ana Hernando | First Assistant Director |
| Directing | Juan Galiñanes | Second Unit Director |
| Directing | Isa Escrigas | Third Assistant Director |
| Costume & Make-Up | Beatriz Antelo | Hair Designer |
| Costume & Make-Up | Pedro Raúl de Diego | Special Effects Makeup Artist |
| Costume & Make-Up | Nacho Díaz | Special Effects Makeup Artist |
| Costume & Make-Up | Jesús García | Special Effects Makeup Artist |
| Costume & Make-Up | Paula Gámez | Special Effects Makeup Artist |
| Costume & Make-Up | Alberto Hortas | Special Effects Makeup Artist |
| Costume & Make-Up | Jordi Morera | Special Effects Makeup Artist |
| Costume & Make-Up | Raquel Álvarez | Special Effects Makeup Artist |
| Costume & Make-Up | Juan Olmo | Special Effects Makeup Artist |
| Editing | David Gallart | Editor |
| Sound | Maika Makovski | Original Music Composer |
| Crew | Óscar Franco | Stunt Coordinator |
| Crew | Fany Veiga | Stunt Coordinator |
| Crew | José Carlos Extremadura | Stunts |
| Visual Effects | Félix Bergés | Visual Effects Supervisor |
| Crew | Gara Caballero | Visual Effects Editor |
| Visual Effects | Berta Coderch | Visual Effects Producer |
| Visual Effects | Roberto García | Digital Compositor |
| Visual Effects | Elena González | Visual Effects Coordinator |
| Visual Effects | Clara López | Visual Effects Coordinator |
| Visual Effects | Cristian Martin | Digital Compositor |
| Art | Astrid Mayor Ramis | Title Designer |
| Visual Effects | Antonio Miravalls | Visual Effects |
| Visual Effects | Quico Noizeux | Digital Compositor |
| Visual Effects | Laura Pedro | Visual Effects Supervisor |
| Visual Effects | José María Rincón | Visual Effects |
