Gray gives meaning to the term ""full-throttle horror"" in her jet-propelled tale of an 18-wheeler's race with a demon. A likable trucker who believes that ""the best cure for any kind of unhappiness was perpetual motion,"" Josh Spiller is fleeing commitment to his pregnant girlfriend when he accidentally runs down a child in rural Furnace, Va. Although cleared of responsibility, Josh can't shake the conviction that the child was deliberately pushed in front of his rig, and that the pious townsfolk are covering up a murder. Back on the road, Josh senses something indescribable pursuing him. It could just be his guilt, but a hitchhiker persuades him that a more sinister game is afoot. In a nod to M.R. James's classic ""Casting the Runes,"" Josh discovers that he has been given a scrap inscribed with an invocation to a fire elemental, and that to save his life he must pass it ""willingly but unknowingly"" back to whoever gave it to him--within the next five days. The pace never flags once Josh burns rubber back to Furnace, even when the story detours through dead-end subplots about the fate of Josh's unborn child and Furnace's dark history of ritual sacrifice. Although the plot doesn't manage the same consistency that Gray brought to the many layers of her debut, Trickster, it abounds with unpredictable twists and ends with a suspenseful climax that both fulfills its eerie potential and does justice to its intelligently drawn characters. (Oct.) FYI: This is the second riff on M.R. James's story to appear this season. James Hynes's Publish and Perish pays homage to James with a novella called ""Casting the Runes.""