The Hardys pay a visit to Bayport's newest martial arts school and find that someone's trying to run the place out of the neighborhood.

In trying to free their friend Holly from the clutches of a murderous mountain cult, the Hardy boys find that the lunatic Rajah and his followers have spread to their own home town.

When a new Broadway musical is sabotaged by death threats and accidents that nearly kill an understudy, the Hardy brothers enlist the aid of Nancy Drew, whose likeness to the show's lead actress enables them to arrange an inside investigation.

What is the mysterious organization known as ATAC (American Teenagers Against Crime)? And how are detective brothers Frank, Joe, and Fenton Hardy involved? Uncover the clues to these questions as the Hardy brothers take to the skies to crack a diamond-smuggling team of sky-divers and then encounter a young woman whose identity has been stolen (or at least that's what a young woman claiming to be Joy Gallagher claims).