Mary Astor
I watched this on TCM last night and I thought she was the best part of this movie! Her acting was superb, I enjoyed every scene she was in. She is one of my favorite classic movie actresses, even if the movie she is in stinks, she is worth watching :) There's actually a YouTube video of classic movie bloopers with her and Bette Davis, and although you can't see Mary Astor's face, you can hear her and it's hilarious. The first one is just Bette Davis and then the second one is the part where Sandra says she wants her baby back. It's from 4:41-4:53.
https://www.youtube.com/watch?v=8Xw3d0hTztc