Story is confused and confusing, and while with the aid of heavily-shadowed lighting and mausoleum-like architecture, a certain eeriness has been achieved, it’s all a poor imitation of things seen before.
Boris Karloff occupies a spooky manor built over the ruins of a world war fort where 10,000 soldiers drenched the valley in blood in a terrible military defeat caused by Karloff’s treachery. That is told but not shown. Bela Lugosi is a batty doctor just out of a cruel jail in which he spent 15 years. Also due to Karloff’s unworthy character.
Clash of the two eyebrow-squinting nuts involves an American bridal couple temporarily caught in the manor. It is the playful notion of nasty Karloff to make the bride Exhibit A in a devil cult of which he is the head, and it is the revenge of Lugosi to torture his enemy by skinning him alive.
Corpses standing upright in glass cases and operating table murders are other tricks which the story uses. Edgar Allan Poe’s name is used for publicity purposes. All that is used is the title which belongs to a Poe short story.
Karloff and Lugosi are sufficiently sinister and convincingly demented.