An 11-year-old boy is home one day while the rest of the kids are at a camp. Gregor is alone with his crazy old grandmother and his little sister, Boots. He goes to do the laundry one day, and follows his sister down a hole into an underground realm. The children are met by a giant, sentient cockroach, who takes them to a human castle, where Gregor is told he cannot return to the Overland. After trying to escape with Boots through the Waterway, Gregor is attacked by two massive, talking rats. The..y are rescued by four bats with human riders. Back at the castle, Vikus decides that Gregor truly is the warrior spoken of in a prophecy. Vikus then takes Gregor, Boots, Henry, and Luxa on a quest, but first they must find the other members. They set off to find the people/creatures needed. First they go to the crawlers. They take two crawlers, Temp and Tick. They then go to the spinners to get two spinners. The Queen of Spiders refuses and holds them prisoner. They break out eventually, thanks to Luxa, and escape to the Dead Land. There, Vikus can take them no further, so he brings a rat named Ripred to guide them to the rat's home. There, Henry reveals himself to be a spy and summons an army of rats and the rat king to kill Gregor. Gregor realizes that the rats will try to kill him, no matter the danger, so he jumps off the edge of a cliff, and sure enough, the rats follow him. As Gregor falls, Henrys' bat catches him instead of Henry, so Gregor is saved but Henry is not. The team goes back to Regalia, and Ripred gathers a political party of rats to help him ascend to the throne. Gregor, Boots, and their father return home to the Overland.Książka nie dostępna w polskiej wersji językowej