The business man Domenico (Marcello Mastroianni) charms the much younger teen country girl, Filumena (Sophia Loren). She is enamoured with him and bedgers him to take her into his home as a semi-official mistress. But years later Domenico prepares to marry an even younger shopgirl, Filumena has to show she is not too naive for a cunning plan with which to marry Domenico.