In 1937, actress Molly Barry tires of looking for work on the London stage and applies for a job as a housekeeper, then rushes back to her boardinghouse to prepare for the interview. She tells her fellow actors, including Lily and Julia, about her decision and frets about her lack of references. Just then, Kitty Burroughs, a former exotic dancer who has recently married an upper class newspaper publisher, arrives to visit Molly, her ex-roommate, and Molly persuades her to act as her reference. While Kitty is awaiting her signal from Molly, Peabody, the butler of the Graham household, shows up to interview Molly. Molly convinces Peabody that she is a genuine housekeeper, but Peabody's own true identity is revealed when Kitty recognizes him as Harry Phillips, an actor who left the profession due to his heavy drinking. Molly is overjoyed, as she thinks that Peabody will readily hire another actor, but he refuses, stating that the household can accomodate only one "professional." Desperate for the job, Molly lures Peabody to a pub and gets him drunk, then takes him to the Graham home. In the morning, she presents herself to John Graham, the head of the household, as the new housekeeper, and the hungover Peabody cannot repudiate her without revealing his past. Graham, a stuffy ex-politician, surprises Peabody by accepting Molly and her cheery additions to the house, but the other servants are disgruntled. While Molly is making the best of the situation, Graham consults with his friend, Jamie McDougall, who wants him to stand for Parliament. Graham protests, as his career was ruined years earlier by his scandal-causing, unfaithful wife, but McDougall insists that Graham should return to serve his country. After Graham and Peabody travel to Suffolk to meet with party leaders, Molly discovers that Angus, the gardener, chef Pierre Patard and the other servants are defrauding Graham by ordering too many groceries and selling the garden's flowers. Molly threatens to expose the thieves, but they retaliate by quitting and leaving Molly alone to run the large household. While she is cleaning the fireplace in Graham's study, Molly finds a newspaper clipping about Graham's faithless wife and realizes that she is the cause of Graham's gruff demeanor. That evening, Molly is surprised by the arrival of Jimmy, Graham's teenaged son, who is supposed to be away for his school holidays. Jimmy is ill with a fever, and Molly's kind, motherly behavior prompts the lad to confide in her that his father does not like him. Jimmy, who believes that his mother died while he was very young, thinks that Graham dislikes him because he reminds him of his dead wife. Molly tucks the lad in, and the next morning, receives a telegram from Peabody instructing her to prepare a formal dinner for that evening, when Graham will entertain Sir Arthur Burroughs, the influential publisher of the London Transcript . Desperate for staff, Molly enlists her pals from the boardinghouse, and soon, Lily and Julia are acting as the housemaids, Pops is the butler, Musette is the cook, and Ronnie is working in the garden. Peabody is flabbergasted when he sees the actors in the house, but takes it all in stride. Despite complications, such as the arrival of Kitty, who is married to Sir Arthur, the dinner is a success, and Graham is assured of Sir Arthur's support. The night ends unhappily, however, when Graham overhears Jimmy imitating him while relaxing with Molly and the others in the kitchen. Graham angrily sends Jimmy up to his room, but when he tries to fire Molly, who admits that she and the others are actors, she quits and accuses Graham of being a bad father. The next morning, Jimmy apologizes to his father, and after a long talk, father and son are reconciled and Graham agrees to re-hire Molly and the others. While Graham and Jimmy are upstairs, however, Molly is confronted by Mrs. Graham, who has returned from South Africa, where she moved with her lover years earlier. Mrs. Graham has come back to blackmail her former husband, but Molly sends her off with a promise to bring the money to her hotel. After Graham assures Molly that, with her help, he will become a better father, she is determined to prevent Mrs. Graham from ruining his life again. With the assistance of her friends, Molly tricks Mrs. Graham into believing that she has killed someone, and the frantic woman leaves England without bothering Graham or revealing her presence to Jimmy. Molly and the staff return to the house just before Graham and Jimmy come back from a pleasant evening out, and after Jimmy and the others go to bed, Molly and a reformed Graham enjoy a song and a snack in the cozy kitchen.