California promoter Myron C. "Lefty" Merrill is left holding the bag when his partner leaves town with the prize money for a marathon dance contest. Lefty is in love with the contest winner, Ruth Waters, but her widowed mother, Lil Waters, intends for her daughter to marry a rich man, not someone like Lefty. Determined to pay Ruth her share of the prize money, Lefty promotes a phony treasure hunt on the pier. He escapes with the entrance money just before a desperate mob destroys the pier looking for the promised prize, but learns that the Waters have left California for New York after illegally selling the furniture in their furnished apartment. Lefty follows the Waters east, where he discovers Ruth working as a model and dating wealthy fashion photographer John Hayden. After he watches Ruth struggle to rub in some sticky face cream, he imagines that all her efforts are burning calories and decides to promote it as a reducing cream. He solicits endorsements from society women and his campaign is extremely successful. Lil now considers Lefty to be a good match, but Ruth refuses to marry him until she knows how success will affect him. Lefty takes a job promoting a backwater college, and his success earns him an honorary degree and the attentions of student Marlene Reeves. Marlene's father, Charles, hires Lefty to promote Grapefruit Acres, a development in Florida. Lefty asks Ruth to accompany him and marry him there, but she refuses, saying that they will be married when he returns to New York. Later she and Lil decide to surprise Lefty in Florida, but they are surprised instead when they discover him having breakfast in Marlene's hotel room. After Lefty is arrested for false advertising because no one actually wants to buy grapefruit, he begins a campaign extolling the eighteen-day grapefruit diet, and soon the charges are dropped. Then when Lil tells him that Ruth is marry to Hayden, Lefty tricks her into admitting that she really loves him.