Aircraft tycoon Grant Matthews (Spencer Tracy) is goaded into running for president by his politically ambitious longtime girlfriend, newspaper publisher Kay Thorndyke (Angela Lansbury). At the suggestion of unscrupulous campaign manager Spike McManus (Van Johnson), Matthews reunites with his long-estranged wife, Mary (Katharine Hepburn), for the sake of appearances. But when the idealistic Mary learns of Kay's behind-the-scenes role, it throws the entire campaign into turmoil.