Hardy-guttene Series by Franklin W. Dixon

A dying criminal confesses that his loot has been stored "in the tower." Both towers of the looted mansion are searched in vain. It remains for the Hardy boys to make an astonishing discovery that clears up the mystery and clears the name of a friend’s father.

Timber wolves, a Rocky Mountain blizzard, and a mine cave-in are only a few of the perils Frank and Joe Hardy encounter during their search for the principal members of a notorious gang responsible for a payroll robbery. In the old Montana mining camp of Lucky Lode, the young detectives puzzle over a series of mysterious events. A piano-playing ghost haunts the long-abandoned dance hall. Eerie blue lights flash from the hilltop cemetery in the dark of night... moreTimber wolves, a Rocky Mountain blizzard, and a mine cave-in are only a few of the perils Frank and Joe Hardy encounter during their search for the principal members of a notorious gang responsible for a payroll robbery. In the old Montana mining camp of Lucky Lode, the young detectives puzzle over a series of mysterious events. A piano-playing ghost haunts the long-abandoned dance hall. Eerie blue lights flash from the hilltop cemetery in the dark of night. Strange men arrange a meeting at Shadow the Bear. A suspect disappears through a curtain of frozen ice. How are these events related to the men who kidnapped the boys in Chicago? Who booby-trapped the helicopter which flew the young detectives to the ghost town? And what ever happened to Bart Dawson who seemingly deserted his gold-mining partners twenty-five years ago? Clue by clue, Frank and Joe cleverly fit into place the scattered pieces of this dangerous puzzle and come up with the astonishing solution. less

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 fin - 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... moreThe 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 fin - 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 Viking of old, Frank and Joe, with their close pal, Chet Morton set off on a perilous quest in the Northwest Territories to recover the valuable artifact before the robbers can decipher the symbols leading to the buried treasure. less

Frank and Joe Hardy become involved in a case affecting national security when Joe dials a wrong telephone number and gets the Pentagon. Two words-- "Bombay Boomerang"-- that the boys hear before the line goes dead plunge them into a whirlpool of danger and intrigue. At the same time, Frank and Joe must save their father from a murderous gang stealing mercury shipments in the Baltimore harbor... moreFrank and Joe Hardy become involved in a case affecting national security when Joe dials a wrong telephone number and gets the Pentagon. Two words-- "Bombay Boomerang"-- that the boys hear before the line goes dead plunge them into a whirlpool of danger and intrigue. At the same time, Frank and Joe must save their father from a murderous gang stealing mercury shipments in the Baltimore harbor. With clues linking the mercury thefts to the top secret Super S missile mysteriously stolen from a government arsenal. In a race against time, the three Hardys foil a diabolical scheme to create widespread havoc in the United States. less

Frank and Joe are called upon to find a wealthy industrialist's son who has mysteriously disappeared. The only clue in the case leads the two young detectives to South America, where the intrigues of evil adversaries almost cost them their lives. Only through their courage and perseverance do the Hardys solve one of the toughest cases they have ever tackled.