Harried paleontologist David Huxley (Cary Grant) has to make a good impression on society matron Mrs. Random (May Robson), who is considering donating one million dollars to his museum. On the day before his wedding, Huxley meets Mrs. Random's high-spirited young niece, Susan Vance (Katharine Hepburn), a madcap adventuress who immediately falls for the straitlaced scientist.