Set in 1830s Istanbul, The Janissary Tree offers an intimate glimpse into the exotic world of the late Ottoman Empire. The mood in the Empire is conflicted, wavering between the desire to regenerate the declining traditions which maintained the Empire for centuries, and the forces of change which seek to revolutionize the Empire and bring it into step with the modern powers of Europe.

Investigator Yashim finds himself hurled into the center of these struggles. A eunuch attached to the court of Sultan Mahmut II, Yashim is called upon to investigate the disappearance of four officers from the New Guard, the Empire's recently commissioned modern army. When the seraskier shows Yashim the grisly remains of one of the officers, the gravity of impending events suddenly becomes clear to him. Something very large and dangerous is about to happen. The ritualistic nature of the murder sets Yashim on the scent of the Janissaries, a supposedly extinguished group of mystical mercenaries who for four hundred years had been responsible for defending the Empire from its foreign enemies, and for maintaining law and order within. As Yashim follows this lead, the larger picture comes into focus, where the threat of revolution and counter-revolution looms just below the surface of everyday life in Istanbul. It's up to him now to find the kidnappers and save the Empire before it is too late.