Mary and Bruce Banning, with their child Elizabeth, share a maisonette with Sabina and Rodney Pennant and their child Valentine. Mary and Bruce are out at work all day, but Rodney, a film scriptwriter, works at home, while Sabina runs the house with the assistance of Nurse Blott, Nanny to Elizabeth. A row breaks out between Rodney and Sabina due to her inefficiency as a housewife, and in his anger Rodney is rude to the Nanny, who gives notice. Bruce and Mary return home from work and during the ensuing argument Rodney leaves the house in a temper, but telephones later and asks Sabina to meet him at the Savoy for dinner. She is taken there in the car of Victor Manifold, an admirer of hers, who opportunely calls, and Bruce and Mary are left to fend for themselves. A fortnight later Mary announces joyfuly that she has secured the services of a new Nanny, and in order to prevent trouble they all plan that the children shall be introduced to her as brother and sister. In the excitemnet of the Nanny's arrival Sabina burns the supper, and Rodney again leaves the house in a temper. Mary and Bruce decide to eat out, leaving Sabina to look after the children. Victor arrives, and while consoling Sabina, kisses her, but is seen by Bruce who returns unexpectedly. After Victor's departure Bruce himself falls for Sabina's charms, and he is mistaken for Sabina's husband by the Nanny when she enters the room. Rodney comes back, sees Bruce and Sabina embracing and once again leaves the house. On his return the next morning he is annoyed to find that there is a plan afoot for Bruce to pose as Sabina's husband so that the Nanny should not learn the truth. He stalks out once more. The plan fails, however, as the Nanny sees Rodney making up the quarrel with Sabina and kissing her, and she leaves the house in disgust. The four of them are at heart glad to be able to relax, and as the curtain falls another of the usual squabbles breaks out between Rodney and Sabina.