Frank and Joe's immersive murder mystery experience turns into a real missing person's case.

Hired to locate an old Spanish cannon, the Hardy brothers uncover an even greater treasure after perilous underwater adventures.

Frank and Joe race against time to retrieve a scientist’s top-secret invention before thieves get their hands on it. But the young detectives soon discover that they are involved in a mystery far greater in scope than just safeguarding the invention. When Joe is kidnapped, this incident starts Frank of on a chase that could end disastrously for him and his pals.

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

One exciting event follows another when Frank and Joe Hardy are hired to apprehend the pickpockets who have been plaguing Solo’s Super Carnival. When their friends Tony Prito and Biff Hooper exhibit a stuffed whale dug up at a construction project, they all but put the carnival out of business. In this thrilling mystery the young detectives pit their wits against a gang of thieves whose bizarre identification, a three-part whale tattoo, proves...

A banker who has been receiving threatening notes enlists the help of the Hardy boys. Before long, the young sleuths find themselves entangled in the investigation of a notorious band of thieves.

A million dollars’ worth of gold bullion has been stolen from the Wakefield Mint under strange circumstances. Mr. hardy is asked to investigate but before long his life is threatened, and he asks Frank and Joe to help him. The boys fly to Zurich, Switzerland, hoping to get information at the Swiss Gold Syndicate and to find the man who has stolen a valuable ancient gold figurine from a New York museum. Their search on both counts seems futile...

The Hardys purchase a Chinese junk to use as a ferry service, in order to make some money over the summer. It soon becomes apparent that others are very interested in the ship.

In one of the most dangerous and intriguing cases of their careers, Frank and Joe Hardy help their father investigate a series of mysterious car accidents. Each of the drivers had seen a signpost marked DANGER shortly before his accident. The young detectives investigate, only to discover that the signposts have vanished. The attempted theft of a secret experimental motor and the kidnapping of a famous race horse are part of this thrilling case, which...

There is not time for explanations when Mr. hardy telephones Frank and Joe form the West Coast and sends them flying off to England to help his old friend Professor Rowbotham. Their stay in East Anglia begins with a weird omen, as they witness the bizarre funeral of an old witchmaster. From then on, strange things happen. When the Hardys learn about the strange disappearance of Lord Craighead, the plot deepens. Danger follows them to Ireland as Frank...