Set over a long weekend in East Anglia this is the chilling story of a rivalrous friendship - as told with deceptive casualness by the narrator Ian. It opens with a surprise phone call from an old university friend inviting Ian and his wife Em for a few days by the sea. Their hosts Ollie and Daisy are a golden couple and the scene is set for sunlit relaxation.
But dangerous tensions quickly emerge and in the stifling atmosphere of a remote cottage in the hottest days of summer Ollie and Ian resurrect a bet made twenty years before. Each day becomes a series of challenges for higher and higher stakes setting in train actions that will have irreversible consequences.