Showing Dead Lagoon by Michael Dibdin

Aurelio Zen returns to his native Venice to investigate the disappearance of a rich American resident but he soon learns that, amid the hazy light and shifting waters of the lagoon, nothing is what it seems. As Zen is drawn deeper into the complex and ambiguous mysteries surrounding the discovery of a skeletal corpse on an ossuary island in the north lagoon, he is also forced to confront a series of disturbing revelations about his own life.