Casting against the grain
It was nice to see Gale Sondergaard, who usually played sinister parts, get a sympathetic role in this movie. She looked so benign and attractive, I didn't recognize her at first. Gloria Holden rarely had such a big part in an "A" picture, and never the romantic lead, which is what her role in Zola passed for I guess. Unless you count lesbian vampire as a romantic lead. She looked terrific, too.
Also, Harry Davenport, usually seen as kindly, dignified gentlemen, was quite sinister in this one.
He maketh His sun to rise on the evil and on the good... St. Matthew 5:45