On the high ground above the great city, Roy and Helen live in brittle affluence inside a weary marriage. Of their four children, three have long vanished into the sprawling, sluttish metropolis beneath: Marcus the dotcom entrepreneur, Shona the shocking Britart princess, and Danny - the one nobody will talk about.

But the last child Zack itches to know more about his lost brother; and gets his chance when the smooth surfaces of family life are abruptly blown apart. Roy is sacked on his fiftieth birthday, stages an unconventional protest in the office doorway and rapidly finds himself a homeless exile in the city's darkest streets. It is Zack's chance to escape down the hill in turn, while his mother Helen makes a bizarre decision of her own.