Drawing inspiration from an Edgar Allan Poe tale, this is a reasonably good drama—though it feels rather confining—focusing on “Guy” (Ray Milland) and his fear of being entombed alive. The movie begins with the disinterment of his father’s coffin, revealing that the deceased wasn't entirely lifeless when initially interred. Understandably, this causes his son to become anxious about a similar fate befalling him, leading him to obsessively try to prevent it—a course of action that damages his marriage to the youthful and increasingly worried “Emily” (Hazel Court) and strains his relationship with his sister "Kate" (Heather Angel). As expected, appearances are deceptive; the narrative presents several misleading clues, leaving the viewer uncertain about who Milland can truly rely on. The pacing is skillfully managed by director Roger Corman. However, Milland delivers an over-the-top performance throughout, his exaggerated expressions and theatrical acting style undermining what is otherwise a strange story of dread. Hazel Court—who was memorable in Corman’s "The Raven" (1963)—doesn't have substantial material to work with, and the conclusion, while unusual, isn't particularly satisfying. It remains watchable though.

Source on TMDB