In "Operation: P.I.A.N.O. (Pesky Instrument Advances New Operative)", the Kids Next Door attempt to stop a shipment of pianos - otherwise known as kid torture devices. Numbuh 4 is injured when he goes against orders during the mission and is stunned to find out that his temporary replacement is a hamster! In "Operation: Z.O.O. (Zoologically Obsessed Octogenarian)", the owner of a zoo where the attractions are kids instead of animals captures the Kids Next Door. They are forced to work together with the Delightful Children From Down the Lane, who are also imprisoned, in order to escape.
—Anonymous