When signs of vandalism begin to appear at the Morton family farm, Chet and Iola Morton are worried that their grandparents are in danger, and with their parents away, they ask Frank and Joe Hardy for help.

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

When a crime syndicate takes over Bayport's reservoir Frank and Joe Hardy help their detective father solve the sinister mystery.

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

On an ice-bound, snow-covered island, Frank and Joe attempt to solve the mystery of a boy's disappearance and the theft of a priceless collection of antique medals.

When the Hardy boys eagerly agree to assist their friend Jack Dodd and his father in locating a family treasure, the two young detectives are unaware of the baffling complications that will arise. The only clue to the long-lost treasure is a cryptic message written by a Pilgrim ancestor. But when Mr. Dodd and Jack are accused of stealing cars and then mysteriously disappear, Frank and Joe are confronted with a triple mystery. Have their friends run...

When Frank and Joe try to get hold of a top secret invention, they are put on the trail of jewel thieves and smugglers. Joe is kidnapped and Frank starts off on the chase.

While on a relaxing safari vacation to Nairobi, Frank and Joe Hardy become involved in finding the culprits responsible for killing innocent animals for their tusks and skins.

On a visit to Germany the Hardy brothers investigate the theft of plans for a newly invented submarine and the mysterious disappearance of valuable coins and paintings.

One exciting event follows another when Frank and Joe Hardy are hired to apprehend the pickpockets who have been plaguing Solo's Super Carnival.