At the outbreak of World War I, Robert W. "Bobby" Jenks enlists in the U.S. Army, and as he is undersized, he finds himself assigned as a cook in the supply department. In the pocket of an oversized shirt, given to him by a practical joker, he finds a letter from Anna May Jackson, a Brooklyn factory girl, who expresses her admiration for big westerners. Bobby begins a correspondence with the girl, exaggerating his muscular development, proposes marriage by proxy, and is accepted. Returning home, he passes himself off as Richard Jenks, the pal of Robert Jenks, her correspondent; then the genuine Richard Jenks arrives, and Bobby induces him to carry out the deception. After many complications, the truth is revealed, and Anna May confesses her love for Bobby, despite his stature.