When the war ends, American ex-soldier Jerry Mulligan, decides to stay on in the city which has enchanted him so much. He lives in a small and cheap pension, located in a narrow street in one of the poorer quarters, trying to scrape a living as an artist.
One of his neighbours in a close-knit and friendly community is a concert pianist, Adam Cook, who is living off the proceeds of a music prize. During one of the periods when his scholarship funds had run low, Adam had found work as accompanist for the big singing star Henri Borel and by chance they meet again. The re-union is a happy and high-spirited one and Borel tells his friend of his love for Lise, who he is soon to marry. While the pair are together, Jerry arrives, hoping to borrow some money from Adam but Adam is just as penniless and Borel steps into the breach.
Jerry sets off for Montmartre where he puts up his easel and starts to paint. Soon he is totally absorbed in his art, as oblivious of the passing crowd as it is of him, but an American girl tourist stops to peer over his shoulder and this distracts and annoys him. She leaves hurriedly when Jerry loses his temper. Then another woman, wealthy Milo Roberts, steps forward and asks Jerry if he will shout at her as well. Her forceful personality impresses the young American and she persuades him to sell her two paintings. Milo sends him home in her chauffeured car and a strange friendship is started.
Milo has fallen for the young painter and, to hold his attentions, she persuades him she is a lover and patron of the arts who wants to help finance his career. Meanwhile, Jerry meets a pretty young shop girl and they fall in love. The setting is perfect with all Paris and its charms at their feet but the idyll is shattered when the girl reveals, sadly, that she is engaged to be married. She is Lise, Borel's fiancée.
At the Beaux Arts Ball, Milo realises that Jerry's love will never be hers but Borel is oblivious to what has happened and continues to advise Jerry on love. It isn't until he overhears Lise bidding Jerry a sad farewell that he realises it is he who has the problem, not Jerry. True to his character as a real gentleman, Borel sends Lise back to Jerry and love triumphs.