Eleven-year-old Jo loves Halloween and all things horror, but she doesn't believe anything bad could ever happen in Fels, her small German hometown. When Hektor, her annoying older brother, disappears on his way home from school, Jo assumes he is playing a prank on her. But then both her father and grandma forget Hektor's name, and his stuff mysteriously disappears from his room. With the adults of no help whatsoever, Jo starts an investigation of her own, uncovering an old legend that has haunted the children of Fels for centuries. A monster lives in the rye fields, and draws children into its world under the roots. With two days until the gate between their worlds closes, and only Hektor's obnoxious best friend to help her, Jo must figure out a way to rescue her brother, or lose him forever.