Kate (Clemence Poesy) and Justin (Stephen Campbell Moore) are an affluent couple in a tony London suburb awaiting not just the arrival of their first-born, but also the new tenants who will rent the apartment downstairs following the death of its previous inhabitant. When Jon (David Morrissey) and Teresa (Laura Birn) move in - he a self-assured businessman, she a self-possessed professional - Kate and Justin set out to befriend their neighbours.

Things get off to a good start: the overgrown back garden is restored to its immaculate former glory, and, lo and behold, the new couple is also expecting a child. They seem to have lots in common, but things take a strange turn at their first dinner party, and yet another with the birth of Kate and Justin's baby boy. These twists, and many others, provide the dramatic underpinnings on which Farr can turn the screws on his four main characters.