Preston Sturges was one of the great comedy directors of the 1940's. 1941's Sullivan's Travels is one of the funniest and most touching films ever made. It's amazing to me that he made that and The Lady Eve, one after the other, in the same year.
The Lady Eve is a screwball romantic comedy starring Barbara Stanwyck as Jean, part of a father-daughter con team that sets her sights on Charles "Hopsy" Pike (Henry Fonda), the heir to a huge Ale company. She arranges a chance meeting with him on a ship on his way home from a year studying snakes in the Amazon. He falls right into Jean's hands, and falls head over heels for her, as she starts planting the seeds for the big swindle.
Things are complicated, however, when Jean starts to fall for Pike as well. When Pike's bodyguard, Muggsy, smells a rat, calls in some favors, and reveals her true identity to him, a heartbroken Pike dumps Jean. Jean, furious at being spurned, then decides to get her revenge by reentering his life as a different woman, The Lady Eve, and bleeding him dry.
The two leads are perfect in their roles. Stanwyck is excellent as the manipulative and hard-hearted Jean/Eve, who keeps her vulnerability always under the surface, and Fonda is the perfect mark as Pike, filled with a nearly endless supply of naivete and trust. When Jean reappears in his life as Eve, Pike rationalizes that Jean would never come into his home without a disguise, so the resemblance must be a coincidence.
The Lady Eve is one of the great comedies. It's smart, silly, and romantic, all at once. The dialogue is endlessly clever, and loaded with the kind of snappy one-liners that the best movies of the time (many of them Preston Sturges movies) were known for. I do like Sullivan's Travels more than this, but you really can't go wrong with either.