The Black Book — Orhan Pamuk

Galip is a lawyer living in Istanbul. His wife, the detective novel-loving Ruya, has disappeared. Could she have left him for her ex-husband, Celâl, a popular newspaper columnist? But Celâl, too, seems to have vanished. As Galip investigates, he finds himself assuming the enviable Celâl 's identity, wearing his clothes, answering his phone calls, even writing his columns. Galip pursues every conceivable clue, but the nature of the mystery keeps changing, and when he receives a death threat, he begins to fear the worst.