If you've heard The Foxes of Harrow being compared to Gone With the Wind, it's probably because the novels have a similar setting. The movies really aren't alike. I've since looked up a synopsis of the novel, and it's quite different from the 1947 drama. So, in case you don't like the movie, you might still be interested in checking out the scandalous novel, which spans more time and goes through the Civil War.
In the movie, Rex Harrison plays an illegitimate Irish rogue who makes his way to America by gambling and sometimes cheating. He doesn't care about being a scoundrel, because he always lands on his feet and he climbs his way back to the top. He gets an influential friend, Richard Hayden, in the crème of New Orleans society, and quickly he amasses a fortune and becomes a legitimate suitor to Maureen O'Hara, a fiery debutante. She should know exactly what she's getting into, because she's seen his roguish ways first-hand, but after she marries him, she seems shocked and disgusted by his character. They have a child, but because his housekeeper threw away some good-luck voodoo dolls made by one of their slaves (remember this is pre-Civil War times), their house gets a curse on it and things go from bad to worse.
I'm neither a Rex Harrison nor a Maureen O'Hara fan, so I wasn't the best target audience for this movie. I appreciated the intense melodrama of the story, and part of me is tempted to read the book, but since I find Rex unlikable anyway, I couldn't really get behind the story. He's unlikable enough even when you're supposed to root for him, let alone when he's a scoundrel!