This is the last Philo Vance novel, and it is actually incomplete. Evidently Van Dine wrote in three stages. First was a very rough draft; second was a fuller draft with most of the dialogue; last was a final draft with a lot of other details and narrative info added in. When he died, the second draft of this novel was completed; the final draft was not. So it's a bit hard to read at times, although the overall flow of the plot is easy enough to follow. Interestingly, it would seem that stripping out a lot of the extraneous information would make the mystery easier to solve, or at least easier to follow, but I'm not sure that's the case.
It is hard to judge this novel against the earlier entries in the series, although it certainly didn't seem like it was on the way toward being appreciably better than the last few weak ones (but I should mention this is the only one not set in New York City--it's at a rural farm in the dead of winter). It probably deserves 2 stars but I gave another star because the book is traditionally published with Van Dine's "twenty rules for aspiring mystery writers." As one who has read a lot of mystery novels, I found his advice quite germane, and I wish more writers would read it! It's a lot of "don'ts," and I'll list a few: don't have the detective turn out to be the perp; if there are multiple murders, don't have multiple murders; red herrings are fine, but the clues need to be such that the careful reader has a chance to solve the murder; don't have the butler do it, or any other minor character, etc.
This book is hard to find but I found a complete PDF from a Canadian source online that was easy to read.