The Sea by John Banville

This title is the winner of the 2005 Man Booker Prize.

When art historian Max Morden returns to the seaside village where he once spent a childhood holiday, he is both escaping from a recent loss and confronting a distant trauma. The Grace family had appeared there, in that long-ago summer, as if from another world. Mr. and Mrs. Grace, with their worldly ease and candour, were unlike any adults he had met before. But it was his contemporaries, the Grace twins, Myles and Chloe, who most fascinated Max. He grew to know them intricately, even intimately, and what ensued would haunt him for the rest of his years and shape everything that was to follow.