After her extravagant, irresponsible sister Valerie marries Dennis Moore, Joan Colby sets her sights on John Fletcher, a notorious San Francisco playboy. Joan's old-fashioned father, Colonel Sam Colby, complains that John, who inherited his father's shipping business, is so lazy that he is driving his company into bankruptcy. In spite of the colonel's disapproval, Joan pursues a romance with John and announces to Valerie that, while she does not love John, she intends to marry him. Joan explains to her sister that marriage is the business of women and that love is a complication to be avoided. Although John responds deeply to Joan, whom he regards as "virginal" yet alluring, she worries that he will soon return to his previous lover, Monica Page. While Joan woos the marriage-wary John, Monica begins to telephone him and makes known her desire to rekindle their affair. Consequently, Joan arranges with Valerie to have their father show up at John's apartment one night when she is alone with him. As hoped, the colonel is shocked and demands that John marry Joan immediately. Because Joan is willing, John agrees but, as he explains to Joan on their honeymoon cruise, intends to divorce her after they return to San Francisco and accepts Joan's suggestion that they end the marriage in six months. Two months later, John is already feeling anxious about his "captivity," but tells Joan he appreciates her efforts to make a legitimate businessman out of him. To that end, Joan has arranged with her father to have his friend, Oliver Lane, the postmaster general of the United States, meet John at a dinner party in the hope that Lane will grant the Fletcher shipping line a profitable government contract. At the same time, Valerie confides in Joan that she needs $1,000 to pay clothing debts but is afraid to ask for the money from Dennis, who has threatened to leave her because her extravagances have repeatedly landed her in debt. Although she refuses to ask John for the money, Joan does agree to pawn her mother's engagement ring to help her sister. When Joan is only able to raise $500 for the ring, Valerie secretly asks John for a loan, lying that she needs $1,000 to cover household expenses because of Dennis' failing business. Overhearing John giving Valerie a check, Joan denounces her sister and demands that she grow up and resolve her financial problems on her own. Furious, Valerie reveals Joan's marriage trick to John, and stricken by the truth, John leaves and goes to the waiting Monica. Joan follows him to Monica's and, after apologizing for her deception, confesses that she has truly fallen in love with him. Joan then returns home, where Lane and her other dinner party guests are waiting. To Joan's delight, Lane agrees to give the absent John his business. Then, just after a drunken but repentant Valerie prepares to tell her husband the truth about her spending, John returns to his devoted wife, bringing her a box of gardenias, her favorite flower, to signify his love.