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 adifferenttune.
Now he and his rats must learn a new concept:evil. . .