In Miami, Florida, newly-hired stockbroker Steve Bennett is sweet-talked into trying to double the $10,000 investment of Gwen Saunders, the niece of his boss, T. T. Ralston. Ralston later tries to force Steve to sell worthless stock to one of his best customers, but Steve insists on telling the truth about the stock. Ralston and his partners, Tom Van Dusen, who is wooing Gwen, and Dick Donnelly, who is married to Ralston's daughter, then bet Steve that he cannot tell the truth consistently for twenty-four hours. Steve lays out the $10,000 on the bet, which starts at 4:00 p.m., with the stipulation that no one can reveal the bet and it cannot be called off. The partners stick by Steve's side during the next twenty-four hours, most of which are spent on Ralston's yacht. Steve, forced to be completely honest, insults Ralston's guests, and everyone is offended by his overall behavior. Later in the evening, showgirl Linda Graham, to whom Dick promised that Steve would invest in her show, comes aboard looking for Steve. When Mrs. Ralston and Van's mother overhear Linda repeating lines from her show, they misinterpret the conversation and assume that Linda is Steve's estranged wife. At bedtime, the partners steal Steve's clothes to prevent him from sneaking out, but he steals a dressing gown from Linda, who has been placed in the cabin next to his in hopes they will "reunite." Steve sneaks into Gwen's room at her invitation and, having fallen in love with her, assures her that he is not married. The next day, everyone is mad at Steve: Gwen, because she finds out he was in Linda's room the previous night; the mothers, because he was in Linda's room and is not really married to her; and Van, because he is jealous. To make matters worse, Linda, who has engineered a ruse with Dick, vows that Steve is her errant husband and father of her child. Just before 4:00 p.m., Mr. Bishop, head of a charity organization for which Gwen raised the $10,000, demands to see the money. Gwen, who overhears the partners discussing how they plan to trick Steve into losing, stalls for time to help him. Steve confidently lies about how he has invested the money when the clock strikes four. The partners think they have won the bet because they set the clocks ahead, but Steve's assistant Samuel had corrected the clocks. Steve's victory means that he has doubled Gwen's money, and he tells everyone that he had made a bet for which he was supposed to lie for twenty-four hours, thereby reinstating his honor and earning him a kiss from Gwen.