It's Christmas in the Harper household, and as expected, chaos ensues: Janey has some shocking news, Nick is up to his usual antics, and Susan is trying out a new Christmas recipe.

After doing some Christmas shopping, the Harpers find themselves stuck in an underground train that has broken down. Susan tries to help everyone escape, Nick sells 12 bottles of mineral water to people and Michael gets a girlfriend called Claire.

Ben and Susan look back at the last few years of family conundrums and troubles after Ben breaks Susan's leg.

Christmas in the Harper household means something special to everyone. For Susan it's the ultimate control opportunity; for Ben, the ultimate nightmare. Nick is having a typically unusual Christmas, Michael's girlfriend is getting much too serious, and Janey comes home with something unexpected which nobody actually wants.

There is a thunderstorm going on, and after being scared, Michael and Janey join Ben and Susan in their bedroom. They are soon joined by Nick who, thanks to now being a party reviewer, brings with him Adam Hart-Davis, Anthony Head, Myleene Klass, Nell McAndrew, Dermot Murnaghan, Clive Russell and Jamie Theakston.

The Harpers' family Christmas looks like being even more fearsome than usual for Ben, as Susan is giving grandson Kenzo a third birthday party to remember - but one which Ben will prefer to forget.

Ben would do anything to get out of Christmas at home. Michael and Alfie make the most of an empty house and Janey learns that it's tough being a mum.

Ben's efforts to buy Susan's Christmas present get him into trouble, and Susan's letter from The Palace means a change of holiday plans for everyone.

It is December 2039, and the Harpers are gathering together to celebrate Christmas. With a "greed gift exchange", a rival cousin and a Nativity play battle, there may not be too much room for peace and goodwill.

Merry Christmas and a happy New Year from the Harpers - except that Christmas does not look like being very merry for one little girl. And, whilst it may be a new year, Ben sees a chance to renew an old battle with his next-door neighbour.