The yogi Agor Singh (Nils Asther) arrives at the gates of the Ingston mansion and is admitted, but inside all is not well. The highly strung Miss Ingston, who lives there with her crippled brother (Ralph Morgan), is concerned about the spots of blood that have been appearing around the place, and as the housekeeper Mrs Judd (Doris Lloyd) scrubs away at the stairs, she announces to her that she has called for a psychiatrist to prove that she is not insane. Mrs Judd is most unhappy at this news, and as if that were not bad enough the maid, Milly (Janet Shaw) is not sure she wants to stay in this company for much longer - and it might have been better if she had fled right there and then...
Not to be confused with Night, Mother, the sensitive drama starring Sissy Spacek and Anne Bancroft, this was a B-movie horror designed strictly for the lower half of a double bill. Which might seem odd, as its plot was lifted from a higher profile picture of about ten years before: if you've seen Doctor X, then you'll have an idea of how this one turns out. But less than a horror movie this was more of an old dark house mystery of which there was a plethora around this time, where the audience is kept guessing whodunnit for about an hour and is meant to be stunned at the revelation at the climax, although if you go by the maxim that it's going to be the person you least suspect who is the killer, it probably won't come as much of a shock.
A faint note of melancholy is struck in that the two stars who received top billing here as presumably the most recognisable actors in this are pretty much squandered in supporting roles, with Lionel Atwill especially relegated to what amounts to barely more than an extended cameo in the first half. Bela Lugosi does a little better, yet this was another of his sinister butler parts, something that seems like an indignity for the man who played Dracula to be the servant. In fact, he's not even all that sinister here, blanching at the sight of blood and dutifully following orders: we don't even get to find out what happens to him at the end during the fiery finale.
But Night Monster was more of an ensemble piece all round, and at the beginning when it's not too clear what is going on it can come across as genuinely strange for a while, whether that's down to a lack of coherence or specific design is for you to judge. This is precisely the kind of scenario that a roving reporter would have fit right into, but we don't have one of those, so you have to make do with an author of crime fiction, Dick Baldwin (Don Porter), who for some vague reason has journeyed up to the mansion just in time to save the psychiatrist, Dr Lynne Harper (Irene Hervey), who has been stranded when her car broke down at the same time as Milly, returning to the house to fetch her suitcase, is murdered.
The way you know that there's about to be an attack in the grounds is that the frogs stop croaking, a neat idea that supplies more unintended giggles these days than chills. But most of the action takes place inside the mansion, where a group of various suspicious and not so suspicious types have assembled to see Singh use the mystic powers of his mind to conjure up a skeleton holding a box containing a ruby and a curse out of thin air - like you do. This is our chief hint at what is really going on, as the murders are still occuring, and the doctors invited to the Ingston house are being picked off one by one. The most dubious character is the chauffeur (Leif Erickson), who seems to be one step away from being a sex maniac the way he propositions and even manhandles almost every woman in sight, but don't be fooled. It's all wrapped up in an explanation that doesn't really explain much, but that's part of the fun of this minor but not unenjoyable chiller.