This was first published in 1942. The author has written numerous murder mystery novels, usually of the locked room type, and other seemingly impossible situations. Many are out of print now, but still obtainable second hand. My daughter got hold of this one, complete with yellowed pages, but the antique state of the book fits with the slightly archaic style of writing.
I found it a little difficult to read - I guess writing styles have changed somewhat in the last half century or more. The author takes the omniscient role, jumping from head to head with impunity, which is something no self-respecting writer would attempt these days. In this context, a murder mystery where every character is initially suspect, it is disconcerting to be told categorically what this or that one is feeling. I wasn't at all sure who I could trust, or even whether I could trust the author.
The mystery itself wasn't too difficult, surprisingly. I guessed the culprit early on, and spotted A Big Clue about half way through, so the ultimate reveal wasn't much of a surprise, although there were enough red herrings to keep me wondering if I was right until the very last moment, and plenty of background details which I could have guessed if I'd been paying attention. But there were a number of implausibilities which kept it from being a real success.
My main complaint was the characters. The female protagonist was quite the most spineless creature I've ever had the misfortune to read about. I just wanted to slap her. The others were very cardboard, without a single one who felt like a real, rounded human being. And the detective (actually a psychologist of some sort) was downright irritating, claiming to have worked out the whole story at an early stage but refusing to give any hints. In fact, the author had to jump through hoops to manage this, with several instances where he's about to reveal something, only to be conveniently interrupted or else there's a clunky jump to the next scene. So a nice mystery but not the best written ever. Three stars.