A terrified three-year-old boy is found clinging to a wire fence at the side of a country road. His mother had whispered to him to never let go, then she vanished. The only clue found by authorities as to the child’s identity is a photograph of two summering teenage girls and a letter presumably written from one to the other.

Sixteen years later, Walker Devereaux is in Toronto to discover the truth about his biological mother, of whom he has a dim memory. Working as an after-hours cabdriver, Walker befriends Krista, a demanding, pretty, wheelchair-bound night dispatcher. Krista and Walker become fast friends, and she can’t help but involve herself with Walker’s quest to understand his shrouded identity. Soon enough, though, their off-hours sleuthing turns perilous. Walker and Krista’s wooded countryside veers this duo ever closer to that of another abandoned boy who has transformed himself into the embodiment of his own desperate, violent, and sinister pathologies.