The colonel Daniel Blimp, of the secret British service, travels to Bangkok to investigate the murder of the Brittish Ambassador happened during a holiday in his residence. Blimp receives the help of Keats, agent of the secret service. Both men discover that the man who shot against the Ambassador is blind, and it takes the black skin as a result of a strange phenomenon of mutation.
Unfortunately the movie Trip to Bangkok, Coffin included is not yet available on HBO Max.
| Editing | Lina Romay | Editor |
| Directing | Lina Romay | Assistant Director |
| Directing | Jesús Franco | Director |
| Costume & Make-Up | Juana de la Morena | Makeup Artist |
| Camera | Enrique Díaz | Camera Operator |
| Writing | Jesús Franco | Screenplay |
| Writing | Edgar Wallace | Novel |
| Camera | Ángel Ordiales | Camera Operator |
| Production | Antonio Mayans | Production Manager |
| Production | Jesús Franco | Producer |
| Sound | Jesús Franco | Music |
| Camera | Juan Soler | Director of Photography |
