In Paris, an oil executive does a favor for an older Parisian businessman by romancing the latter's daughter.

Wealthy American oilman Paul Chadwick wins a court case in Paris against French attorney Michel Boullard by seducing the judge, a woman. Boullard flies to New York for a reunion with his daughter Lauren, whom he has not seen in 25 years, and on the plane he meets Chadwick, who promises a favor in compensation for the injury to Boullard's French pride. In New York, Boullard discovers that his daughter is a spinster psychologist engaged to mother-dominated Arnold Plum, and he asks Chadwick to have an affair with her. Posing as a patient, Chadwick seeks Lauren's help in fighting off sexually aggressive women. Falling for the scheme, Lauren shelters him in her apartment. He gets her drunk on champagne and takes her to his apartment when she passes out. Mickey, the switchboard operator, helps undress her while her future mother-in-law, Mrs. Plum, watches, unaware that Lauren is her son's fiancée. Upset by her indiscretion, Lauren tests herself by taking Arnold out to drink champagne; again she passes out. Chadwick sneaks her back to his apartment. This time she is recognized by Mrs. Plum. Boullard takes pity on his daughter, tells her about the plan he concocted with Chadwick, and helps her plan a counter-attack. Lauren invents a Spanish lover, and an ego-shattered Chadwick goes on a drinking spree. Boullard steps in again to change the course of events, and Lauren is tricked into accepting Chadwick's marriage proposal.