Into the house. Down the stairs. Through the dripping dark of the cellar. Someone is there. Someone that shouldn't be there. 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. With the death toll rising and the city reeling in terror, Brennan and Marina race to expose a predator more soullessly evil than any they've ever faced—and one who is hiding in plain sight.