Franklin W Dixon

The Hardy boys search for their father when he disappers while investigating a house that is either haunted or a hide-out for criminals.

"Drop case or else danger for you and your family." This ominous warning and others that follow cause Frank and Joe to suspect a link between the counterfeiting case they are investigating and a secret case their father cannot discuss involving national security.

The Hardy brothers interrupt their investigations of jewelry-store holdups to answer a plea from their cousin on a New Mexico cattle ranch.

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 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.

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

Frank and Joe, the Hardy boys, solve a mystery involving a magician, American secret agents, and international spy ring, and a Scottish castle.