Ellen McNulty sells her New Jersey hamburger stand and heads west to pay a surprise visit to her son and his new bride. When Ellen arrives, her daughter-in-law mistakes her for the maid she has hired for a big party her husband is throwing to impress his boss. Rather than cause any embarrassment, Ellen goes along with the charade, which leads to many complications. Written by Daniel Bubbeo White-collar working stiff but upwardly mobile Val McNulty meets, quickly falls in love and marries socialite Maggie Carleton, who has no money of her own. Thus, they live in a modest apartment on Val's wages. At the same time, Val's widowed mother, Ellen, without funds of her own when the bank forecloses on her family business, a hamburger stand, decides to move from New Jersey to Ohio to live with Val. Her plans change when she finds out about Val's upcoming nuptials as she doesn't want to upset Val's life with his new wife. She also doesn't want to meet Maggie until she feels she has enough money at least to make herself presentable to someone of Maggie's social class. Once Ellen feels that is the case, she goes over to Val and Maggie's where a case of mistaken identity ensues when Maggie assumes Ellen is the cook hired for a dinner party happening that evening. Wanting to help her new daughter-in-law, Ellen doesn't correct Maggie. Although Val eventually finds out who the cook is, Ellen convinces him - blackmails really - that she can be of better assistance to Maggie as Ellen the live-in full-time household cook, than Mrs. McNulty her new mother-in-law. Ellen ends up being more than just a cook as as hired help, she is privy to many of the thoughts and schemes of those who don't want to see Val and Maggie's marriage succeed, namely Maggie's ex-boyfriend/Val's boss George Kalenger Jr., Val's ex-girlfriend Betsy Donaldson, and Maggie's snobbish mother Fran Carleton. Ultimately, Maggie finds out about the deception and decides to leave Val because she feels he didn't trust her to love someone of working class and he is only hiding his mother's identity to further his career. It isn't until Val risks a business deal by revealing Ellen's true identity to all that Maggie returns to her loving husband. Along the way, Ellen finds some personal happiness of her own.