Book of Souls

For ten years, every year at Christmas, the bodies of young women were found in Edinburgh. They were all naked, freshly washed. All had their throats slit. The last victim was Kirsty Summers, the fiancée of Detective Constable Tony McLean. But the Christmas killer made a mistake, and grief-stricken McLean tracked him down and caught him. Twelve years later, the maniac is killed by a cellmate, and that winter the murders start again. Did the police make a mistake and arrest an innocent man? Or has the Christmas killer acquired a copycat? Or is there some other, more sinister explanation?