Er wordt een belangrijke ontdekking gedaan wanneer een Egyptisch document uit de elfde eeuw teruggevonden wordt. Deze leidt op zijn beurt naar de plek waar de kelk van Het Laatste Avondmaal zich bevindt. De zoektocht overbrugt enkele eeuwen en beslaat tevens gebeurtenissen die beschavingen wereldwijd hebben gevormd.
Nee, helaas is Onyx: Kings of the Grail nog niet beschikbaar op Netflix in Nederland.
| Directing | Roberto Girault | Director |
| Crew | Valentín Diez Morodo | Thanks |
| Production | Óscar Cifuentes | Producer |
| Production | Óscar Cifuentes | Executive Producer |
| Production | Pedro Palacios | Executive Producer |
| Writing | Roberto Girault | Writer |
| Writing | Luis Reneo | Writer |
| Writing | Margarita Torres | Writer |
| Camera | Rafael Bolaños | Director of Photography |
| Sound | Eduardo Ortega | Original Music Composer |
| Production | José Jaime Linares | Production Director |
| Art | Itziar Sagasti | Production Design |
| Editing | Adoración G. Elipe | Editor |
| Costume & Make-Up | Giovanna Ribes | Costume Designer |
| Sound | Carlos Lidón | Sound Recordist |
| Sound | José Luis Alcaine Bartolomé | Sound Designer |
| Directing | Patricia Ordás | First Assistant Director |
| Directing | Chris Downs | Second Assistant Director |
| Directing | Daniel M. Caneiro | Script Supervisor |
| Production | Carla Hool | Casting Director |
| Crew | Mabel Villagra | Technical Advisor |
| Production | Eduardo Lis | Production Manager |
| Lighting | Raúl Pavón | Gaffer |
| Camera | Jorge Casabán | Key Grip |
| Crew | Miguel Olarieta | Special Effects |
| Costume & Make-Up | Alicia López | Hair Department Head |
| Costume & Make-Up | Sonia de la Fuente | Makeup Department Head |
| Camera | Marco Mastropietro | Still Photographer |
| Directing | Luis Reneo | Second Unit Director |
| Visual Effects | Helmuth Barnert | Visual Effects Supervisor |
| Sound | Miguel Ángel Caprara | Foley Artist |
| Writing | Margarita Torres | Book |
| Writing | José Miguel Ortega | Book |
