Devastated by the death of his father, Zach Webster's life gets worse when his mother moves him away from his friends in the big city to Whitmer, a tiny town tucked in the farthest corner of western North Carolina. They settle into the home of his late great-great uncle, an inventor whose secretive laboratory is still in the basement, hidden behind a locked steel door, the key lost somewhere in the old, Victorian house.

With little to do for entertainment in the dying town, Zach and his new friends — twin boys and their younger sister — turn to exploring the nearby national forest, where they meet a strange recluse, an enormous man with fantastic, almost supernatural abilities. Amazing things happen when they're with this giant, and together they become entangled in a bizarre mystery that will forever change their lives and those of everyone around them.