Force of Evil (1948) on Netflix

It's one thing for a lawyer to defend a client in the numbers racket, but it's another for him to become partners with the man. Joe Morse crosses that ethical line with his gangster client, Ben Tucker. Together they've got a scheme to shut down all the illegal banks in the city, and buy up the ones they want. Joe has an older brother, Leo, a man with heart trouble; and Leo has one of these illegal banks. Joe wants to do something good for Leo, to force his brother out of his penny-ante racket and come work for the big boys. The trouble is, Leo is happy with his small, if not quite ethical, business. His employees are like family to him. His secretary, Doris Lowry, is like a daughter. He wants nothing to do with his little brother's scheme and nothing to do with gangsters. But Joe won't give him a choice. Joe has a strong will - strong enough to make the sweet and innocent Doris fall in love with him. But he's still too weak to turn straight and save himself, and everyone connected to him, from disaster.