Nightshade City (Nightshade Chronicles, #1)

Deep beneath a modern metropolis lies the Catacombs, a kingdom of remarkable rats of superior intellect. Juniper and his maverick band of rebel rats have been plotting ever since the Bloody Coup turned the Catacombs, a once-peaceful democracy, into a brutal dictatorship ruled by decadent High Minister Killdeer and his vicious henchman, Billycan, a former lab rat with a fondness for butchery. When three young orphan rats -- brothers Vincent and Victor and a clever female named Clover -- flee the Catacombs in mortal peril and join forces with the rebels, it proves to be the spark that ignites the long-awaited battle to overthrow their oppressors and create a new city: Nightshade City.