There's a new brother team in town -- Ed and Peter Mason -- and they've got Frank and Joe's number. Ed has already put Joe down on the wrestling mat, and Peter's robots are sure to put Frank's science project to shame. And now the Masons are putting the moves on Callie and Vanessa. All's fair in love and war, but the Hardys don't even know what's at stake.

An even bigger test awaits them. Fenton Hardy has taken charge of a multimillion-dollar jewelry exhibit at the Bayport Museum, and his supersophisticated security system has suddenly gone haywire. Realizing that much more than their reputations are on the line, and Frank and Joe close ranks with their father in the fight of their lives...against a criminal mastermind!