Though not invited Ben tags along with his kids and Alfie to take part in the local pub quiz where Alfie notices that a member of another team seems to be cheating. Ben is ready to have it out with him, especially when the man turns out to be the school bully who used to make young Ben's life a misery. However circumstances conspire to put the bully in a different light.
Michael applies to join MI5 and Janey starts dating an older man, James, who nonetheless is rich and successful and the kind of son-in-law that Ben would be quite happy to welcome to the fold. However, when he is seen kissing another woman, is he the real deal?
Whilst Janey lands herself in hot water by fabricating a Swedish girl-friend for a depressed Roger, Susan is visited by an old friend Margot, who is going through a divorce and wants to borrow a man to make her husband Phil, who is seeing someone, jealous. Inevitably she borrows Ben and they go out to the restaurant where Phil is - succeeding in annoying him. Next morning Ben wakes up the worse for drink. Has he really slept with Margot?
When Michael admits to going to see a therapist but will not tell his parents why, they are intrigued as to the reason. Could it be that his apparently talking to himself has something to do with it? They decide to get into the therapist's office to look at the files. Alfie finds himself in the unusual position of having not one but two possible girl-friends moving in with him.
Ben's uncle Norris dies, leaving ten thousand pounds - to Susan, for her support following the loss of his Mildred. Ben, also expecting a large legacy, buys an expensive suit but it turns out that Norris has only left him a box of old clothes. However Ben would seem to have a winning lottery ticket. Unfortunately it's in the suit that Alfie gave to Norris's son, thinking it belonged to the dead relative and Ben must retrieve it without causing offence.
Susan wants a dog but the assessor from the dogs' home deems her unsuitable so Ben goes to the kennels to sneak one out for her, only to find she is already there and about to call in the press as a protest against the assessors' decision. She then handcuffs Ben to one of the bars and leaves him to be her spokesman to the reporter.
New patient Jessica proves to be an undercover spy for the Cavitex dental company and she feels Ben's behaviour warrants his going on a retraining course, along with Roger. Feeling patronized and irked by the presence of the Cavitex mascot giant bear, Ben falls asleep during a talk but on waking learns that there is to be an exam on all the facts he has just missed. Perhaps a little bribery is in order. Back home the family gets drunk on home brew.
Susan, stranded at an Albanian airport, is charmed when a handsome American calling himself the Doctor rescues her and invites her to travel the world with him. Ben, meanwhile, has lunch with old college friend Jeremy, now a celebrity dentist with an international clientèle and a successful autobiography. However, after a few drinks he confesses that he hates his life style, envies Ben, and wants to discard all his perks. Can Ben talk him out of it?
In a clip show to celebrate the show's hundredth edition Susan and Ben try to help Kenzo with a school project about his family by recalling some of their past exploits. Janey and Michael use the project to snipe at each other and Kenzo ends up bored by the whole experience.
It's Christmas 2039. Ben looks like an octogenarian but Susan, thanks to moisturisers, still looks middle-aged. Janey has ballooned, Mikey has lost all his hair and is resorting to an ill-fitting wig and Roger, thanks to an accident at the zoo, is just a head in a glass case. Kenzo is late in arriving, giving the family time to look back on some of their worst Christmas days ever, though the worst one of all time, as Kenzo reminds them, was when Uncle Richard came to stay.