On a shimmeringly hot Sunday in May, Louise is at a neighbour's pool with her daughters - and glaring at her resentfully is her estranged husband Barnaby. While the children splash and shriek in the cool blue waters, she lies blissfully back in the sun and dreams of Cassian, the charismatic new lawyer in her life. The day seems perfect.
But suddenly the bliss is shattered. The consequences of a terrible accident develop into a drama of recriminations, jealousy and legal power-play. Friendships crumble, the village is split, and the needs of a child become secondary to the dangerous contest in which the grown-ups are engaged.