Ruby Nolan, a soda jerk in Solomon Bimberg's San Diego drugstore, has a boyfriend on every ship, precipitating a melee among competing factions. In revenge, they try to persuade the ace gunner (McCoy) on the Mississippi to fall for her; he refuses, but they accidentally meet and the inevitable happens. At a dancehall in Tijuana, Ruby gives $100 to the manager to be offered as a prize to any couple who will be married on the dancehall floor, but when her rejected suitors appear, Gunner McCoy thinks she is playing him for his money. Solomon places a bet with some crooked gamblers on Gunner in a shooting match; swallowing her pride, Ruby induces Gunner to desist from drinking, and he wins the target practice. When he sees that Ruby is sincere, they are happily united.