Whilst Rona spends Christmas alone,all her ex-boyfriends being otherwise engaged, the Porters spend the season with Bette and they hate it, Bill recalls painful childhood Christmas times whilst Ben imagines himself in a scene from 'Misery' with Bette breaking his legs and tying him to a bed to make him stay at her house. They have to watch TV shows they hate,play Consequences - which only David finds funny - and suffer the heating on full blast. Bill tries to explain to her mother her feelings but things start to look up when Bette,hypnotized by the tree lights,falls into a trance. As the titles roll the cast perform Christmas songs.
On Christmas Eve the Porters and Rona set out to meet Bette and Pearl at a hotel but get lost in the fog and are nervous when they hear on the radio about an escaped criminal. They make their way to a deserted old house and one by one the three adults set off to get help but never return. Next morning the children find them,stuck in the middle of a minefield,requiring David to guide them to safety. The two old ladies meanwhile have got stoned on some strange tobacco they have found. On Christmas morning everybody returns to the Porters' house,transformed into a 1950s Hollywood film set for a group rendition of 'Home For the Holidays'.
On Christmas Eve - having ended up with four trees - Bill is amazed when the message 'Is That You,Bill?' appears on David's computer and cannot be switched off. In reply to cryptic messages Bill cripples the country's television transmission and causes bad weather,discovering to her horror that she has the power to make anything she wants happen. After Rona has got in on the act by summoning three scantily-clad and extremely puzzled young marines it suddenly dawns on the family who the 'Bill' is whose wires have inadvertently crossed with David's computer. Before anything else can happen the family flees to a French chateau for a rendition of the song Relaxez-Vous.
On Christmas Eve Ben surprises the others by explaining that he has not bought a turkey as he has won a pig in a raffle. Unfortunately it is very much alive and extremely aggressive,soon eating the family out of house and home. They take it to a farm in the country to join other pigs but it refuses to get out of the van and in desperation Bill phones Battersea Dog's Home. Christine appears and agrees to take the pig but by this time it has given birth to a litter. The cast celebrates with a rendition of 'Rootin' Tootin' Santa Claus'.
Tina is going on a two-week Mediterranean cruise for Christmas so the Porters drive her to Southampton docks,where Ben crashes into the captain's car and the crew's van. Bill,Ben,Rona and David go on board to see her off but discover that the ship has sailed before they can disembark. Whilst they hide Tina tries to sneak them meals but is side-tracked when elderly lecher Fletcher takes a shine to her so Ben dresses as a waiter to steal food but ends up serving the captain's table. Rona finds herself on stage with the ship's dance troupe whilst Fletcher transfers his attentions to a disguised Bill. Finally they are put ashore - in a life-boat, in time for the finale song, 'Be Kind To Your Parents'.
