Evie O'Connor, a secretary at the Trojan Shirt Company in Brooklyn, New York, dreams of a romance with a tall, strong man, one who might fit into a Trojan size sixteen-and-a-half shirt. After learning that many of her fellow co-workers routinely place notes in the pockets of the company's shirts, Evie writes a personal letter and places it in a size sixteen-and-a-half shirt that is destined for an army camp. The shirt makes its way to Private Edgar "Wolf" Larsen, a notorious womanizer, who reads her letter to his pal John Phineas McPherson and, after dismissing it as nonsense, throws it away. Johnny, however, is intrigued by Evie's note and secretly retrieves it. Ignoring Evie's taste for tall and strong men, Johnny, who is short and rather homely, believes that he can win her over with his mind and heart and begins corresponding with her. Complications soon arise, however, when Evie requests that Johnny, who has described himself as being of Wolf's dimensions, send a picture of himself. Afraid that she will reject him if she knows what he really looks like, Johnny sends her a picture of Wolf. One day, Johnny's unit passes through New York, and unable to resist the temptation to meet Evie, he poses as his "friend" Wolf and visits her. Johnny falls instantly in love with Evie, but instead of revealing his true identity, he continues to deceive her. Wolf eventually discovers the letters that Evie sent to Johnny and when Johnny next visits Evie, he make an unexpected appearance at her apartment. Chaos ensues when Johnny clumsily tries to prevent a single intimate moment between Evie and Wolf, and when Evie's roommate, Barney Lee, desperately tries to seduce Johnny. Driven to desperation, Johnny decides to feign drunkenness and causes a scene to force Wolf and Evie apart. His scheme works, and once outside Evie's building, Johnny punches Wolf and orders him to keep away from Evie, insisting that she is not one of his "lollipops." Wolf ignores Johnny's command and secretly visits Evie the next day, but Johnny discovers the truth when he telephones Evie and Wolf answers. Furious, Johnny rushes to her apartment and sets a smoke pot on fire in the hallway to smoke them out. Trying to escape, Wolf falls and knocks his head, and while semi-conscious, proposes marriage to Evie. The marriage does not take place, however, as both Wolf and Johnny are given overseas orders the next day. During their overseas mission, Wolf quickly forgets Evie and marries a French woman, while Johnny continues to write to Evie, shielding her from the painful truth. Evie, meanwhile, discovers Johnny's true identity when she visits his mother and sees pictures of him. Time passes, and Evie, having sworn off both men as liars, shows little respect for Johnny when he visits her. She eventually has a change of heart, however, when she realizes that Johnny is truly in love with her. After revealing to Johnny that she knows who he is, she embraces him and they kiss.