A terrified three-year-old boy is found clinging to a wire fence at the side of a country road. The only clue found by authorities as to the child's identity is a photograph of two little girls and a letter.

Sixteen years later, Walker Devereaux is in Toronto to discover the truth about his biological mother. Working as an after-hours cabdriver, Walker befriends Krista, a smart-alecky, wheelchair-bound night dispatcher. Together, they search for a key to Walker's past. But their after-hours sleuthing steers them ever closer to another abandoned boy who has become the embodiment of desperate, violent, and sinister pathologies.