The Rage of the Vulture - Barry Unsworth

It is May 1908 and the Ottoman world is crumbling. Robert Markham, an Englishman in Constantinople, is newly posted to the British legation with his imperious wife and overly curious son. Markham's hidden life is about to make itself known as he forgets familial and patriotic ties in order to absolve a deep-seated guilt. Twelve years before, he had been involved with an Armenian woman. On the evening of their engagement, the Armenian massacres erupted. Saved by his British citizenship, he witnessed the brutal rape and murder of his fiancee. Amid the breakdown of the Turkish empire, he now seeks revenge.