Thirteen-year-old Adam Harrison lives with his single mother Shelly. The boy's scientist father died when he was young and Shelly has struggled to shepherd Adam through adolescence. By chance, the awkward teenager stumbles upon a metal box hidden beneath floorboards. Inside, he finds recent letters from his father, sent from an address off Route 99. Consumed by rage at his mother's betrayal, Adam hitchhikes to the remote address and discovers that his missing parent is a real-life Bigfoot.