Mice, Hamsters, Guinea Pigs & Squirrels, Action & Adventure, Fantasy & Magic 

When the albino rat Billycan left Trillium at the end of The White Assassin, he fled to the island of Tosca. There, here learns that a former ally, working undercover in Nightshade City, is plotting to free Killdeer's imprisoned evil generals and seize power. He races back to Trillium to join in the coup -- but on which side? So begins the gripping conclusion to Hilary Wagner's Nightshade Chronicles. But something even more sinister is afoot in Trillium City. Rats are disappearing, and so Juniper leads a search party topside, where they discover that Prince Pharmaceuticals, the insidious corporation that tortured so many rats, is back in business, still searching for the secret of Trillium rats' incredible intelligence and longevity. The fate of the Nightshade rats is in Billycan's hands, but can he be trusted? Can he use his connection to the human scientists to ensure the safety of the Lords of Trillium forever? - from Amzon