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.
| Directing | Jesús Franco | Director |
| Writing | Jesús Franco | Screenplay |
| Writing | Edgar Wallace | Novel |
| Production | Jesús Franco | Producer |
| Sound | Jesús Franco | Music |
| Editing | Lina Romay | Editor |
| Costume & Make-Up | Juana de la Morena | Makeup Artist |
| Production | Antonio Mayans | Production Manager |
| Directing | Lina Romay | Assistant Director |
| Camera | Enrique Díaz | Camera Operator |
| Camera | Ángel Ordiales | Camera Operator |
| Camera | Juan Soler | Director of Photography |
