 Susan Applegate, tired of New York after one year and 25 jobs, decides to return to Iowa. Trouble is, when she saved money for the train fare home, she didn t allow for inflation. So the audacious Susan disguises herself as a 12-year-old (!) and travels for half fare. Found out by the conductors, she hides out in the compartment of Major Philip Kirby, a military school instructor. The growing attraction between Susan and Kirby is complicated by his conniving fiancee...and by the myopic Kirby continuing to think "Su-Su" is only 12!