A young reporter is enjoying an upper-class British house party when abruptly, someone is found dead!
I can't say I enjoyed this. There's an entire subplot concerning a Bolshevic satanic cult (?!) that goes nowhere, and isn't even an effective red herring.
This is the first Inspector Alleyn book, and it's clear that Marsh isn't sure how to write him yet. His personality is all over the place: one moment he's burbling Bright Young Things slang, the next he's cold and remote, the next he's romantically morose. It doesn't read like a complex character so much as one without any fixed characterization. The mystery itself is very frustrating, because there's no way it should have worked. The murderer springs out of the bath, pulls on gloves, slides down a bannister face-first, yoinks a dagger conveniently nearby, and stabs his victim who just so happens to be standing with his back directly in front of the bannister? No one on earth would plan a murder that way! And there's no way that Alleyn figured out that the murderer did it that way, when his only evidence was that the murderer wore a glove! How does that prove that someone slid down the bannister face-first, let alone which person did it?
I'll try one more Marsh book, by virtue of her reputation, and then I think I'll call it quits.