the deep end of the ocean by Jacqueline Mitchard

‘Watch your brother,’ says Beth Cappadora to her seven-year-old son Vincent. Only minutes later she turns again and asks, ‘Where’s Ben?’ It’s the moment that every mother fears: for three-year-old Ben is gone. And no one can find him. Despite a police search that becomes a nationwide obsession, Ben has vanished, leaving behind a family that will be torn apart with anguish. Until, nine years later, the undreamed-of happens: a twelve-year-old boy knocks on their door – a boy who does not know them, but who will irrevocably twist their lives a second time…