Curse of the Demon offers the best kind of thriller: one populated by intelligent characters behaving according to their personalities, not the whims of the plot. It avoids cheap jump-scares, preferring shadowy hallways and darkened rooms to keep us on edge. And, for the real horror, there’s Niall MacGinnis.

MacGinnis plays Julian Karswell, a self-professed black magician. Our protagonist, a psychologist named John Holden, played by Dana Andrews, arrives in London to expose Karswell as a fraud. Karswell tries to dissuade Holden, but Holden remains resolute. Karswell then announces Holden will die in three days. Holden is skeptical, but after a series of unexplained events, his skepticism crumbles and he begins to fear for his life.

I loved MacGinnis’s performance. It’s a perfect combination of charm and menace. There’s a terrific scene where Holden has broken into Karswell’s palatial home. A supernatural trap has Holden struggling for his life, only escaping once Karswell enters and turns on the lights. Karswell treats the intruding Holden as one would treat a party guest who’d gotten lost looking for the bathroom. By underplaying the role, MacGinnis makes the character even more sinister.

Yet, despite the solid script, competent direction, and inspired performances, Curse of the Demon falters. The opening sequence sees the titular demon marching toward the screen. A similar sequence occurs at the film’s end. In both, the demon’s mechanical movement and frozen expression scream rubber suit. My wife thought it resembled a homecoming float. These shots do worse than cheapen the film, they undermine any sense of ambiguity regarding Karswell’s powers. Holden is the audience surrogate. His skepticism is our skepticism. But this falls apart when we know Karswell’s powers are real from the outset. Instead of questioning things along with Holden, we grow impatient waiting for him to catch up with what we already know.

We can thank producer Hal E. Chester for the degradation. He added the demon shots after principal photography wrapped. Andrews and director Jacques Tourneur fought him on it. Writer Charles Bennett threatened to shoot Chester dead. They all lost. The studio, Columbia, did cut some footage for the American release, but not of the monster.