As a building awaits demolition, a horrifying discovery is made inside the basement: a cage made of human bones, with a terrified, feral child lurking within. Unbeknownst to Detective Inspector Phil Brennan and psychologist Marina Esposito, they have disturbed a killer who has been operating undetected for thirty years. A killer who wants that boy back. But the cage of bones is also a box of secrets-- secrets linking Brennan to the madman in their midst.