Everyone in the Istanbul neighbourhood of Moda knows the Devil's House. A crumbling Ottoman mansion, and once the home of a princess, it is a place associated with ill fortune. The princess's four children, now in old age, still live in separate apartments on different floors and are rumoured never to speak to each other. Then one of them is found dead, stabbed through the heart, and it is discovered that the other three siblings have met an identical fate. There is no sign of forced entry or burglary, and all evidence must be gained from letters and diaries, but as Inspector Ikmen digs into their past it becomes clear they have been harbouring a secret... Meanwhile a young couple are arrested for a series of seemingly random killings on the streets of Istanbul. They claim to have been squatting in the Devil's House. But this fiendish mystery is far from over and it will take Inspector Ikmen to the darkest and most devilish depths of this ancient city.