I’m not sure why the U.S. title of this 1959 Mexican horror movie is The Black Pit of Dr. M. There’s no pit of any color (unless it’s supposed to be metaphorical) and Dr. Mazali (Rafael Bertrand) is never called Dr. M. The original title, Misterious de Ultratumba (roughly “Mysteries from Beyond the Grave”), makes more sense. In any case, the film is one of the better Mexican chillers of the period — perhaps because it was directed by Fernando Méndez, a filmmaker praised (even by Guillermo del Toro) for his ability to create a genuinely creepy atmosphere. That’s certainly the case here — and it’s the atmosphere that is the film’s biggest selling point. The story about Dr. Mazali making a deal with the spirit of his dead assistant (Antonio Raxel) to come back from the dead is no great shakes, and it doesn’t always make good sense. (Mexican horror pictures, of course, are not known for making good sense.) What makes the film work is the combination of atmosphere and its parade of over-the-top grotesqueries. In short order, we get a creepy torch-lit funeral, a séance, mystical occurrences, a crazed gypsy woman asylum inmate, disfigurement by acid, murder, a dubiously conceived romantic triangle and what must be the shallowest grave in the history of burials. Now really, what more can you reasonably want?