The Mirror Man (Killer Instinct, Bk. 8)

Sixteen-year-old Jenny Lind is kidnapped in broad daylight on her way home from school and thrown into the back of a truck. She’s taken to a dilapidated house, where she and other girls face horrors far beyond their worst nightmares. Though they’re desperate to escape, their captor foils everyone of their attempts.
 
Five years later, Jenny’s body is found hanging in a playground, strung up with a winch on a rainy night. As the police are scrambling to find a lead in the scant evidence, Detective Joona Linna recognizes an eerie connection between Jenny’s murder and a death declared a suicide years before. And when another teenage girl goes missing, it becomes clear to Joona that they’re dealing with a serial killer—and his murderous rampage may have just begun.