The Harrison family gathers as usual for Christmas in their big Sussex house. This year, however, outside realities are pressing hard: Pamela and John, married for four decades, know that time is catching up with them. And trouble is brewing in the lives of their four children. Cassie, the cossetted youngest, is in the throes of an affair with a married man; Elizabeth, her awkward older sister, is struggling with a faltering second marriage;...