It opens with a snapshot: Kath, at an unknown gathering, hands clasped with a man not her husband, their backs to the camera. Found after her death, the photograph is in an envelope marked DON'T OPEN-DESTROY. But Kath's husband does not heed the warning. The mystery of the photograph, and of Kath herself, propels him on a journey of discovery in which he must peel back the layers of their life together. The unfolding tale reveals a tight web of secrets-within marriages, between two sisters, and at the heart of an affair. Kath, with her mesmerizing looks and casual ways, moves like an insistent ghost through the thoughts and memories of everyone who knew her: Glyn, her husband, a historian past his prime; her sister, Elaine, a garden designer married to feckless Nick; and their daughter, Polly, who oscillates between home and family and the tumultuous new era she inhabits.