Franklin W Dixon

While their father is on vacation, Frank and Joe Hardy attempt to help Burt Worth who is being sued for libel for something he did not write.

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...

Valuable electronic parts containing platinum are being stolen from shipments made by Stanwide Mining Equipment Company's cargo planes, and Frank and Joe Hardy are called upon to assist their world-renowned detective father to solve the baffling case. At Stanwide the boys pose as employees, and become suspicious of their boss's hostility toward them. Is he involved in the racket? And what is the truth behind the plane crash at sea in which Clint Hill,...

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

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.

The Hardy boys' investigation of a museum robbery in England arouses the anger of a coven of black witches. There is not time for explanations when Mr. hardy telephones Frank and Joe form the West Coast and sends them flying off to England to help his old friend Professor Rowbotham. Their stay in East Anglia begins with a weird omen, as they witness the bizarre funeral of an old witchmaster. From then on, strange things happen. When the Hardys learn...

When two suspicious plane accidents occur near an eastern airport, the two Hardy brothers investigate the case and find themselves in greater danger than they anticipated.

The robbery of the treasure in the tower proves to be an exciting challenge to Frank and Joe. Frank and Joe attempt to foil a ruthless espionage ring in their effort to sabotage the United States space program.

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.