Kaper's music
In the 1960s (and long before I'd seen either this movie or A Life of Her Own), my piano teacher assigned me the Previn arrangement of the theme, from a book with the hopeful title "Play Like Andre Previn."
My hands weren't happy (I have teeny hands, and had tension issues back then), but my ear and brooding adolescent heart loved it.
You can find the arrangement here:
http://www.onlinesheetmusic.com/invitation-p313629.aspx
If you listen to the sample, be aware that it's electronically generated, with no expression, and, I think, much too fast.
This arrangement can carry some of the brooding, haunting sound of the original score, if played well (which I'm sure I didn't, way back then -- I think I can pull it off now, though!).