According to Wikipedia, this Ellery novel was, despite its lateness in the canon, written by Dannay/Lee rather than being among the ghostwritten ones. It's also, I'd say, one of the weakest; I bought it on the basis it must be that rara avis, an Ellery novel I hadn't read, then halfway through realized I had read it, and not in fact all that many years ago. That's more or less a literary judgement in itself.

John Benedict invites his three ex-wives to a weekend at his country retreat, where he breaks it to them that in future they're not going to enjoy the same financial benefits from him as heretofore; not surprisingly, he gets bumped off before too many hours have passed. Luckily he'd also invited Ellery and the Inspector to join the party, and so we know the solution to the mystery can't be too very far away. The trouble is that the first of the mystery's two solutions is a rebarbative piece of contrivance (it depends on how a combination of the three women's names could be misheard) and the second -- genuine -- solution relies on a piece of social prejudice that happily most of us regard as history . . . as would the majority of enlightened readers in 1969, I'd have thought. So, while the writing has the trademark zip of the Ellery novels, whoever wrote them, the setup seems artificial and the mystery more-or-less likewise. Not the Queens' finest hour. ( )