Franklin W. Dixon

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

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 notorious gang responsible for a payroll robbery.

"Drop case or else danger for you and your family." This warning addressed to Fenton Hardy not only alarm the famous investigator and his detective sons, but also puzzles them, because Mr. Hardy is working on more than one case. Which one prompted the threat? When more ominous warnings follow, Frank and Joe suspect there is a link between the counterfeiting case they are investigating and a secret case their father cannot discuss since it involves...

Joe and Frank piece together clues connecting a local bank robbery and the kidnapping of two friends. A series of bizarre events in their home town lead the Hardy Boys on a trail of robbers and kidnappers.

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 find the missing deed to an Indians' land, prevent a phony salesman from carrying through a reckless scheme, and help their father solve a top-secret case.

The Hardy boys pursuit of a hijacked collection of stuffed animals and their father's investigation into an industrial spy ring eventually lead to the wilds of Northern Canada.

An archaeological expedition in the West turns into a desperate attempt to capture robbers and an escaped convict.

Two teenage sleuths help their detective father search for a famous rocket scientist whose disappearance endangers the launching of the Firebird Rocket.

With only the slender clue of an arrow-shaped tie clasp, Frank and Joe Hardy pick up the trail of the cunning gang of thieves responsible for a wave of jewelry-store holdups. But their investigations are interrupted when a desperate plea for help comes from their widowed cousin who lives on a cattle ranch in New Mexico. Frank, Joe, and their pal Chet Morton fly there immediately. The mysterious disappearance of one cowboy after another has given Crowhead...