The powers of good are pitted against the forces of evil as the Duc de Richelieu wrestles with the charming but deadly Satanist, Mocata, for the soul of his friend. Mocata has the knowledge and the power to summon the forces of darkness and, as the Duc de Richelieu and his friends remain within the protected pentacle, they are subjected to ever-increasing horror until thundering hooves herald the arrival of the Angel of Death.
| Camera | Arthur Grant | Director of Photography |
| Editing | Spencer Reeve | Editor |
| Production | Anthony Nelson Keys | Producer |
| Writing | Dennis Wheatley | Novel |
| Directing | Terence Fisher | Director |
| Sound | James Bernard | Original Music Composer |
| Art | Bernard Robinson | Production Design |
| Costume & Make-Up | Eddie Knight | Makeup Artist |
| Production | Ian Lewis | Production Manager |
| Costume & Make-Up | Patricia McDermott | Hairstylist |
| Writing | Richard Matheson | Screenplay |
| Crew | Ken Rawkins | Sound Recordist |
| Production | Irene Lamb | Casting |
| Sound | Philip Martell | Music Supervisor |
| Crew | David Toguri | Choreographer |
| Art | Bernard Robinson | Supervising Art Director |
| Camera | Moray Grant | Camera Operator |
| Editing | James Needs | Supervising Editor |
| Sound | Arthur Cox | Sound Editor |
