Franklin W Dixon

After a dying criminal confesses that his loot has been stashed "in the tower", the Hardy boys make an astonishing discovery.

Teenage detectives Frank and Joe Hardy investigate a case of counterfeiting.

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

The Hardy boys and their father solve a mystery involving inexplicable crashes of highspeed race cars being used to test an experimental turbine motor.

The Hardy boys and two friends take a camping trip to the Rocky Mountains in an attempt to locate a gang of credit-card counterfeiters.

The Hardy brothers' visiting Greek pen pal enlists their help in searching for a priceless ancient Greek helmet loaned to and lost by a Hollywood movie company years before.

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

Timber wolves, a Rocky Mountain blizzard, and a mine cave-in are only a few of the perils Frank and Joe Hardy encounter during their search for the principal members of a notorious gang responsible for a payroll robbery. In the old Montana mining camp of Lucky Lode, the young detectives puzzle over a series of mysterious events. A piano-playing ghost haunts the long-abandoned dance hall. Eerie blue lights flash from the hilltop cemetery in the dark...

When thieves hijack a collection of stuffed animals from a country auction, Frank and Joe Hardy pursue the getaway car and are drawn into a thrilling mystery. The recently acquired interest of their best pal, chubby Chet Morton, in taxidermy as a hobby adds fresh twists to the puzzle.

Frank and Joe attempt to foil a ruthless espionage ring in their effort to sabotage the United States space program.