Frank and Joe go undercover as apprentice stuntmen on a major movie.

High in the untamed Adirondack Mountains lurks one of the most fiendish plots Frank and Joe Hardy have ever encountered. On a mission to rescue their good friend Holly from the cult of the lunatic Rajah,the boys unwittingly become the main event in one of the madman's deadly rituals - human sacrifice. Fleeing from gun-weldinig "religious" zealots and riding a danger-infested train through the wilderness, Frank and Joe arrive home to find the worst...

Frank Hardy's girlfriend Callie mistakenly recovers a top-secret codebook and involves them in a network of fraud, corruption, and murder.

Frank and Joe go undercover as big-city bicycle messengers to crack a gang of high-tech thieves.

Frank and Joe investigate the disappearance of a shady investment counselor when their Aunt Gertrude is fingered as the chief suspect.

The young sleuths team up with their father on a desperate mission when a corrupt multinational corporation kidnaps Laura Hardy to weasel its spies into the top-secret Prometheus Computer Corporation, which Fenton Hardy has been assigned to safeguard.

Frank and Joe investigate a murder in the tough logging country around Crosscut, Oregon.

Bright Futures Development has announced the invention of a powerful new solar energy cell, and the Hardy boys have gone undercover to protect it from industrial spies.