Pascali's Island by Barry Unsworth
The year is 1908, the place, a small Greek island in the declining days of the crumbling Ottoman Empire. For twenty years Basil Pascali has spied on the people of his small community and secretly reported on their activities to the authorities in Constantinople. Although his reports are never acknowledged, never acted upon, he has received regular payment for his work. Now he fears that the villagers have found him out and he becomes engulfed in paranoia. In the midst of his panic, a charming Englishman arrives on the island claiming to be an archaeologist, and charms his way into the heart of the woman for whom Pascali pines. A complex game is played out between the two where cunning and betrayal may come to haunt them both. Pascali's Island was made into a feature film starring Ben Kingsley and Helen Mirren.