Leave Her To Heaven was a 1944 bestseller by Ben Ames Williams. The 1945 movie is now much better remembered (in fact it’s one of the half dozen best Hollywood movies of the 40s). I’ve become very interested in tracking down the source novels of some of my favourite movies. I was lucky enough find an affordable used copy of Williams' novel (it is of course long out of print).
The film followed the plot of the book fairly closely, with a few significant and extremely interesting changes.
If you're a fan of the movie the book is worth a look.