Tired of beatings at the hands of his foster parents for both real and fancied misdeeds, 12-year-old George Mellish runs away from home by hopping a freight train and lands somewhere east of the Mississippi River. The first person he meets is Dirty Jim Jelliman who lives in a fantastically filthy hovel. George finds him a kindred spirit as both have suffered at the hands of clean-freak women. It is (really dirty) Dirty Jim who tells George of the mythical 8-foot boogeyman called "The Fool Killer." George gets sick and Dirty Jim takes him to town where Mrs.Ova Faversham takes charge of the feverish boy. When Blessing Angeline, Mrs. Faversham's 10-year-old daughter, tells George that her mother intends to return him to his foster parents, he hits the road again. He meets Milo Bogardus, a young Civil War veteran, who has been robbed of his memory by a war wound, and is as lost in his own way as George. They come upon a camp meeting, where the fanatical Reverend Spotts is conducting a revivalist meeting and during the religious frenzy, George blacks out. When he comes to, he's alone and unaware that the Reverend has been murdered, and starts searching for Milo. He finds a home with small-town store-keepers the Dodds. During supper, Dodd mentions the Reverend's murder and George blurts out that "The Fool Killer done it" and tells them the legend that Dirty Jim told him.That evening, while George lies in bed, a shadow appears at his window. It is the figure of a tall, gaunt apparition, ax in hand ready to strike: "The Fool Killer!"