First, there is trouble in Shantytown. Then a strange craft tries to ram Frank and Joe's boat, a local bank is robbed, and two of the boys' friends disappear. In trying to relate these events, they confront kidnappers who plan to make their father choose between justice and his sons.
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...
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.
When their father asks for help tracking a jewel thief, the Hardy boys find that the trail leads them back to their own hometown. There, they begin a new investigation of a mysterious death which occurred many years ago.
The Hardy boys travel to the Pocono Mountains to help Thomas Maguire, a family friend. When the boys arrive, they find that Maguire is missing, and they must search the mountain for clues. One thing stands in their way: the legend of a witch and the blood-curdling cries heard nightly in the mountains.
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. Other unforeseen problems ensue when the teen-age sleuths become involved in their father's latest case. Fenton Hardy is tracking down a priceless ivory idol...
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.
Frank and Joe travel to the south of France to help teen Village International rebuild a deserted town as a center for refugee children. But a local legend of a haunted castle and its lord who hid a fortune in diamonds within its thick stone walls, stirs up strange noises, spooky lights, and close shaves that convince the Hardys someone is trying to sabotage the project.