When two suspicious plane accidents occur near an eastern airport, the two Hardy brothers investigate the case and find themselves in greater danger than they anticipated.

The Hardy boys and their father solve a mystery involving inexplicable crashes of highspeed race cars being used to test an experimental turbine motor.

Frank and Joe Hardy are determined to bring to justice the vicious criminals who kidnapped their father while he was investigating sabotage of a road-building project in the Kentucky wilderness.

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

The Hardy boys embark on a freighter trip under mysterious circumstances and find themselves involved with a smuggling ring.

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

Frank, Joe & Chet received a phone call about a mysterious visitor & are determined to get a picture of him. One man turns up, but then walks away without attempting to knock on the door. A second "visitor" then arrives. He proves to be Philip Dodge, a lawyer that their father knows. He tells the Hardys that his client, a Mr. Brownlee, is searching for his nephew, Williard Grafton, who, along with a friend called Clifford Wetherby, has vanished. The...

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

Frank and Joe investigate the legend of Whalebone Island when they receive a warning concerning a sunken freighter.

While on Christmas vacation, the Hardy boys find themselves in two mysteries. One is the disappearance of the grandson of their host, and the other is the theft of a collection of antique medals. The investigation pits them against a ghostly prowler and mysterious strangers.