It’s wise to heed Christopher Lee’s warnings, even if you're Peter Cushing! Here, Cushing portrays "Maitland," who receives a disturbing object from his questionable contact, "Marco" (Patrick Wymark). When he discusses this item with his collecting competitor, "Sir Matthew" (Lee), he learns it was stolen from him, and against advice, decides to proceed. It doesn't take long before he regrets that choice. The skull is linked to the Marquis de Sade, and his spirit intends to create further chaos. To achieve this, it can seize control of those nearby, influencing their actions to suit its purposes. Will the doubting "Maitland" succeed where previous generations have failed, managing to defeat this evil presence? This stands out as one of my preferred Hammer films; a sense of dread steadily builds throughout, alongside some inventive camerawork—frequently from the skull’s perspective—and an evocative musical score. The ending isn't what I anticipate after eighty minutes of enjoyable, unrestrained cinematic wickedness. It avoids predictable gore and relies more on psychological elements to generate fear, which I believe is quite effective.

Source on TMDB