Teenage detectives Frank and Joe Hardy investigate a case of counterfeiting

The Hardy boys' investigation of a museum robbery in England arouses the anger of a coven of black witches

On a visit to Germany the Hardy brothers investigate the theft of plans for a newly invented submarine and the mysterious disappearance of valuable coins and paintings.

"Someone is waging war against Paris -- and the Hardys."

When the Hardy Boys set out to solve the mystery of their missing chums, they discover a gang hide-out in a cave on an island along the way.

"The annual Computer Horizons convention has brought the Hardys to New Orleans. The trouble begins in a jazz club down on Bourbon Street. Together with their friend Vanessa, they run into Billy Barta, a local guy from the convention, and its' one encounter they'll never forget... Billy asks Vanessa to dance, Joe gets jealous, then gets into a fight. The next day Joe gets arrested - for the murder of Billy Barta! Billy Barta was into some serious...

When the Hardy boys reached the caves, they came unexpectedly upon a queer old hermit.

Frank and Joe Hardy investigate a mysterious death at the qualifying rounds of a hot dog eating contest.

Frank and Joe Hardy go undercover at a comic book convention to keep movie star Anya Archer safe from death threats during the filming of a new movie.