Franklin W Dixon

Frank and Joe Hardy receive an unusual assignment from their detective father. They are to "break into" the house of a Bayport neighbor, Malcolm Wright and retrieve a top-secret invention that the scientist had hidden in his study before leaving for California. The invention is in danger of being stolen and the boys race against time to beat the thieves at their own game. The young detectives soon discover that they are involved in a mystery far

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A series of bizarre events in their home town lead the Hardy Boys on a trail of robbers and kidnappers.

The Hardy boys' search for stolen gold leads them to an abandoned mine where, in the depths of the earth, they are attacked by outlaws.

Triggered by the disappearance of a brilliant young professor, this mystery takes the Hardy boys first to Kenworthy College, where they find a puzzling message on an examination paper. But then their pal Chet Morton, with his new metal detector, and buddy Biff Hooper, turn up a clue that sends the young detectives on an exciting search in another direction -- to the Honeycomb Caves, on the seacoast. A hot-tempered hermit who considers the caves his...

The search for a stolen boat leads the Hardy brothers to Mexico where they become involved with a band of Indians and a strange smuggling operation.

A banker who has been receiving threatening notes enlists the help of the Hardy boys. Before very long, the young sleuths find themselves entangled in the investigation of a notorious band of thieves.

The search for missing gold takes the Hardy boys to the Yucatán Peninsula where they uncover a second mystery.

The Hardy boys embark on another puzzling mystery when they try to discover who is stealing rare collections of ancient pirate treasure and smuggling them out of the United States.

Their efforts to recover a stolen ancient chess piece lead the Hardy brothers to Hong Kong where they help smash an international criminal organization.