Hoping to avoid yet another awful family Christmas Ben pretends to be ill so Susan calls his bluff and insists on taking him to see a doctor, which results in hospital admission. Meanwhile Janey is desperate to buy Kenzo the latest 'must have' toy and the boys take advantage of Ben's absence to throw a Christmas party. Then the news arrives from the hospital - Ben really is ill and his condition requires surgery.
The Harpers re-encounter the Mortons, a couple they met on holiday, and go to dinner with them. To Ben's surprise - and a good massaging of his ego - the couple ask him to be a sperm donor so that they can try I.V.F. treatment. However, when his results come through, they prove that he has no reason to crow. Janey is annoyed to find that Mark, Kenzo's long-absent father who has come back into the picture, has been married for two years without telling her and expects Kenzo to greet his 'new mummy'.
Elderly patient Henry Phillips dies of natural causes in Ben's surgery, having confessed to Ben that he has a much younger wife Celia and a much younger mistress Stacey. Ben goes to comfort the widow but is mindful that he must keep the two women apart, in which capacity he goes to the old man's funeral. Susan, however, starts to suspect that her husband may be having the affair and, armed with her new mobile phone that takes photographs, follows him.
Susan is accompanying millionaire businessman James Garrett on an art- buying weekend and, due to an oversight, they must share a twin bedroom. Ben is jealous but without foundation. Michael has a university interview and Ben drives him there, stopping to buy him his first pint on the way. Unfortunately this causes Michael to be sick all over the interviewer.
Susan's mother Grace returns from her holidays having got married again. Michael gets the Harpers and Abi, Roger and Alfie on 'The Weakest Link' quiz show where Grace reveals on air that, in 1973, Susan got married to an all-in wrestler called Troy the Punisher in Las Vegas, though the marriage was quickly annulled. Whilst Ben and Susan argue over her little secret Alfie wins the cash prize.
Charlie Briggs, Ben's old student friend, is getting married but it's to a man because Charlie has had gender realignment and is now a woman. Charlie asks Ben to give her away but Ben is lost for words so Susan steps in instead. Roger's domineering mother arrives. She plans to buy Abi and Roger the house next to hers, an idea which appalls Abi and Susan persuades Roger to talk her out of it for his bride's sake.
A party is held on the eve of Abi's wedding to Roger. Abi's mother gets drunk and tries to flirt with Ben whilst Michael and Alfie try to chat up the same girl. On the wedding day bridesmaid Janey gets dumped by her boyfriend over the phone and Abi has cold feet about getting married but Susan persuades her to go through with the wedding.
The Drapers are amongst the Harpers' oldest friends so Ben and Susan are amazed to learn that they are breaking up. However this leads to Ben and Susan having their own domestic argument. Janey gets Kenzo an audition in an advertisement for breakfast cereal but starts to feel guilty when she thinks that she never asked if he wanted to take part. In the event the job goes to her instead.
Susan gets caught shop-lifting an expensive pair of sun-glasses and is taken to court. Despite her protestations, Ben insists on defending her and putting her actions down to the female menopause. The lady judge is impressed by Ben's performance and dismisses the case. Whilst taking Kenzo to the park for Janey, Alfie meets a girl called Melanie and pretends Kenzo is his son to impress her. Janey is less taken with this idea.