Any bloody death will lead Inspectors etin Ikmen and Mehmet S leyman out onto the dark streets of Istanbul. On 21 January, a half-decapitated corpse in the poor multicultural district of Tarlabasi poses a particularly frustrating and gruesome mystery. But as the months pass and the violence increases, it turns into a hunt for that rare phenomenon in the golden city on the Bosphorus: a serial killer.Desperate to uncover the killer's twisted logic as the body count rises, Ikmen and S leyman find only more questions. How are the victims connected? What is the significance of the number 21? And how many Istanbullus must die before they find the answers?