Thea's parents have split up but still seem to be together. Both her siblings are Smug Marrieds. But Thea is newly single and very much wishes she wasn't. When her mother and father plan a great family Christmas, the idea is to make it all great fun and tremendously civilised – not remotely complicated despite the fact that what they will really be celebrating is the final break-up of their marriage and the Moving On to new partners. And the new partners will also be there – and why not? But will they move on? And will Thea manage to navigate her way through the forced jollities and family disasters to find some happiness for herself?