The robbery of the treasure in the tower proves to be an exciting challenge to Frank and Joe. Frank and Joe attempt to foil a ruthless espionage ring in their effort to sabotage the United States space program.

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

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 their detective father asks them to play burglar in order to protect a client's valuable invention from thieves, the Hardy boys find themselves involved in a large and dangerous conspiracy.

While searching in Iceland for a missing sailor sought by an insurance company, the teen-age detective brothers uncover a plot threatening the life of a United States astronaut and the secrets of NASA's moon project.

An assignment from their famous detective father to track down a ring of credit-card counterfeiters takes Frank and Joe Hardy on an exciting camping trip to the Rocky Mountains. The cross-country trek with their pals Chet Morton and Biff Hooper is jinxed from the very first day. Trouble with their tent trailer is compounded by vicious harassments all the way to Colorado. Here their enemies strike at Biff's lovable bloodhound in another attempt to...

The Canadian Northwest beckons Frank and Joe Hardy to mystery and adventure. It all starts when a French-Canadian trapper, Caribou Caron, makes a historical and valuable find–-a carved rune stone left by Vikings centuries ago near Great Slave Lake. When Caribou Caron attempts to sell the artifact to a representative of a museum, it is snatched by thieves. Like the intrepid Vikings of old, Frank and Joe, with their close pal Chet Morton, set...

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