This pre-code film starring James Cagney has him playing Jimmy Corrigan who is a private detective specializing in finding heirs to large fortunes. He's in competition with Alan Dinehart who calls himself a "geneologist" and has just about the same set of ethics Cagney has. The only difference is Cagney lacks the polish of Dinehart and is less a hypocrite.
Now no one ever confused James Cagney with Ronald Colman on the screen and I daresay they probably were never up for the same parts, but Cagney dumbs it down to Leo Gorcey levels in order to contrast himself with Dinehart. It's effective though.
What makes this film special is that the leading lady is Bette Davis who was a year away from finally getting Jack Warner to give her a role with substance in Of Human Bondage. Speaking of class, you can see that Ms. Davis has it in abundance and that she wasn't going to be held down with supportive leading lady roles. Later on Cagney and Davis were given The Bride Came COD when both were big box office names.
Cagney is quite the operator here and I won't tell you exactly what he does, he does bend our legal system over backwards though. And if he's not exactly reformed, he does learn the difference between class and manners.