The Amazing Maurice and His Educated Rodents: Discworld 28

IT'S A RAT-EAT-RAT WORLD...

Every town on Discworld knows the stories about rats and pipers, and Maurice - a streetwise tomcat - leads a band of educated ratty friends (and a stupid kid) on a nice little earner. Piper plus rats equals lots and lots of money. Until they run across someone playing a different tune. Now he and his rats must learn a new concept: evil...