In the Marks of Secret, the Bane drives the nibblers out of the two colonies, so the nibblers send for help by sending back Luxa's crown. A basket full of nibbler pups are found in the stream. When Temp, Boots, Gregor, Luxa, Aurora, Ares, Hazard, and Thalia reach Hades Hall, they discover that some nibblers from the Fount colony had been driven off a cliff. Luxa makes the Vow to the Dead, and, by doing so, declares war on the gnawers. They find Cartesian, the only surviving nibbler. They come across the Bane, who plans to send the nibblers to a place where they cannot return from (Death). He plans to poison the nibblers with noxious gases from a volcano. The rats discover them, and they are lead to the stingers, who give them information about the nibblers. Later, they find Ripred, and witness the mass murder of some Jungle colony nibblers, who suffocate. The volcano erupts, and Thalia is killed. Ripred, Luxa, Howard, Nike, and Aurora try to free the remaining nibblers.
In the Code of Claw, more nibbler refugees are sent to Regalia. The pups are taken care of in the nursery. Gregor and Ares travel to the Fire Lands, where they discover Ripred, York, Perdita,Luxa, Howard, their fliers, and many others trying to free some nibblers. They return to Regalia, where the rats siege the city. The diggers, who joined the gnawers, began digging tunnels underneath Regalia, where the gnawers swarmed in. Many Nibblers, including Cartesian, died in the attack, along with fliers, and humans. In the battle of the Plain of Tartarus, Nibblers attacked the Bane's gnawers, along with a variety of other species. Nibblers became part of the new diplomatic council.