While working on a school project, the members of the McGurk Organization travel back to 1692 and find themselves involved in charges of witchcraft.

On the basis of a clue found in a library book, the McGurk detectives search for the perpetrator and the victim of a crime they think will be committed in three days.

A master criminal known as The Chameleon threatens to disrupt a mystery contest being held in the public library, but J.G. and the other Watchdogs are on hand to investigate.

McGurk and his squad of amateur detectives investigate an epidemic of disappearing pets in their neighborhood.

Ten-year-old Jack McGurk and his fellow detectives match wits with the local police as they track down a runaway newsboy.