Four lives. Four defining moments which will bring them together. Owen Abingdon is haunted by nightmares of the Merfolk. He believes they have stolen his little sister who vanished while he was meant to be minding her on the beach, but he was only a child himself. Is it fair for his mother to blame him? Catherine Hoyle's perfect Christmas with her cousin from America was blighted when they went skating on thin ice and Rosalyn nearly died. Somehow, instead of being praised for raising the alarm, Catherine gets blamed. Sean Madigan grew up on a farm in Ireland. Learning to swim in the Shannon was his way of escaping the bitter poverty of his childhood, but it also incurred his father's wrath. He flees to England, but his heart belongs to the Shannon and her pulling power is ever near… Unlike the other three, Naomi Seddon didn't fear the sea. She'd been orphaned and placed in a children's home in Sheffield and cruelly abused. The sea offered her a way out and she revelled in its cruel power. The "water children" meet in London in the searing hot summer of 1976 and Naomi uses her siren's charm to lure Owen, Catherine and Sean into her tangled web of sexual charm and dangerous passion. A holiday in the Tuscan mountains with a flooded reservoir and its legend of the beautiful Teodora who drowned there brings this emotional drama to a powerful climax. Will the power of family, love and redemption finally help the water children conquer their fears and triumph over their childhood traumas?