David Prentice, a young television producer, pitches a new idea to his executive - a series detailing the everyday life of a happily married couple. Although initially wary, the executive agrees to a trial with a famous couple at the centre of the show. Dismissing the unavailable Oliviers and Attenboroughs, David suggests the theatre actors, and long-term couple, Simon and Laura Foster. The Fosters are going through a serious separation. Simon, a serial gambler, is accused of womanising by Laura. Simon angrily announces his intention to stay with his mother in Leicester. In a moment of calm, Laura makes it clear that she will not take him back this time because she has done many times in the past. Reminded of his lack of work for almost a year and their 18 months shortfall in the mortgage, Simon leaves.
Simon is about to board a train at St Pancras when Bertie, the couple's agent, catches him and explains that David Prentice has offered Simon and Laura their own television show. Initially, Simon balks at the idea, considering the idea of working on television beneath him. But after learning that he and Laura could become national celebrities, he changes his mind. They return to Simon's home and Laura agrees to hear the pitch. Bertie manages to hide their planned divorce from David and talks the couple into accepting the job, not least because of their debts. At a dinner party to celebrate the new job, David introduces scriptwriter Janet Honeyman. The show is newly named - 'Simon & Laura' - and pre-production begins. David's art director visits the Fosters during a rehearsal and decides to re-create their modern house in the television studio. David and Janet take inspiration from Wilson and Jesse, the Foster's house servants, and decide to cast them. Simon and Laura, the consummate professionals, put aside their differences, and within weeks they are national stars.
Despite the show's huge ratings, David's commissioner finds the show lacking a broader appeal and insists on introducing a child. Simon and Laura arrive the following day to learn that a little boy has been written in as a long-lost nephew. A precocious brat, Timothy steals the best lines and causes problems behind the scenes, interfering with equipment and spreading gossip. But the introduction of him to the show is another hit.
Excited about their continued success, David invites Janet on a date and she happily accepts, but immediately the commissioner calls David with a complaint that the program is too unrealistic and dull. He demands new blood in the picture and suggests Simon is killed in an accident. In a panic, David calls Laura to discuss the commissioner's idea and asks her to meet him without Simon's knowledge. Janet overhears his conversation, mistakenly thinking he is asking Laura out for a date. She angrily manipulates Simon into taking her out; eventually he agrees to a weekend in Monte Carlo.
The Christmas show arrives and everyone is anxious. At a pre-meet before the live broadcast, Laura drunkenly confronts Janet about Monte Carlo; Janet responds by accusing Laura of stealing David. Simon and David arrive and all are accused of deceit. With nothing settled, and both actors drinking, the live broadcast begins. Within moments, Simon and Laura ignore the script and start bickering. Soon they are fighting and David and Bertie get involved in an onscreen brawl. With the set demolished, Simon knocked out and David fainting, the commissioner congratulates the team on their most realistic production.
The national press celebrate Simon and Laura's first quarrel but emotions are overwrought on the studio floor. During a rehearsal break, Simon and David make up and explain the reasons behind their deceit towards each other. David reveals he is in love with Janet and states that Laura refused to accept Simon's removal from the show. Seeing their reconciliation, Wilson and Timothy call Laura and Janet into control room. Once there, they switch on the cameras and Simon and David's true feelings are exposed. Laura and Janet rush to make up with their men.
