Scarlet Street [1945]

Chris Cross, 25 years a cashier, has a gold watch and little else. That rainy night, he rescues delectable Kitty from her abusive boyfriend Johnny. Smitten, amateur painter Chris lets Kitty think he's a wealthy artist. At Johnny's urging, she lets Chris establish her in an apartment (with his shrewish wife's money). There, Chris paints masterpieces; but Johnny sells them under Kitty's name, with disastrous and ironic results.