Unlike earlier generations of Marys who used every trickery to secure husbands, Mary the Third questions the validity of marriage in her search for adventure. Unable to decide between quiet, polite Lynn and aggressive Hal, she follows her suitors, along with sweethearts Max and Tish, on an outing, but an attempted seduction sends her home, where she becomes disillusioned by the quarreling of her parents. When they are reconciled, however, she regains her ideals and accepts Lynn.