Jerry Mulligan is an exuberant American expatriate in Paris trying to make a reputation as a painter. His friend Adam is a struggling concert pianist who's a long time associate of a famous French singer, Henri Baurel. A lonely society woman, Milo Roberts, takes Jerry under her wing and supports him, but is interested in more than his art.

Susan Applegate, tired of New York after one year and twenty-five jobs, decides to return to her home town in Iowa. Discovering she hasn't enough money for the train fare, Susan disguises herself as a twelve-year-old and travels for half the price. Caught out by the conductors, she hides in the compartment of Major Philip Kirby, a military school instructor who takes the "child" under his wing.