Rarely do magicians reveal their professional secrets. Consequently Frank and Joe Hardy are amazed when a well-known magician, the Incredible Hexton, offers to reveal the secret of his “Vanishing Man Act” and invited Mr. Hardy to be the subject. When their detective father fails to reappear, his sons are convinced that something sinister is afoot, despite Hexton’s insistence that Mr. Hardy is playing a joke on them. While desperately searching for their father, Frank and Joe find themselves working with SKOOL, a U.S. organization of secret agents pitted against UGLI, an international ring of spies stealing government secrets domestically and internationally. The young detective’s gripping adventures culminate in a dramatic climax when they unmask the secret agent on Flight 101.

Nancy Drew and her friend Bess discover that a rare and valuable Chinese vase has been stolen from the pottery shop of Dick Milton, a cousin of Bess. Dick had borrowed the vase from his Chinese friend, elderly Mr. Soong, and he is determined to repay Mr. Soong for the loss. He tells Nancy that if he can find “the leaning chimney,” he will be on the track of a discovery which will solve his financial problems. Nancy finds the leaning chimney, but it only leads her into more puzzles. Can there be any connection between the vase theft – one of a number of similar crimes – and the strange disappearance of the pottery expert Eng Moy and his daughter Lei?

Why is a wealthy sportsman so frightened by the serpent design on a mysterious balloon that he begs Frank and Joe Hardy to protect him? And who stole the ancient life-size chess king which is to be presented to the winner of the world chess championship? Targets of diabolical enemies, Frank and Joe find a clue that leads them across the Pacific to Hong Kong to help the police smash an international criminal organization.

Triggered by the disappearance of a brilliant young professor, this mystery takes the Hardy boys first to Kenworthy College, where they find a puzzling message on an examination paper. But then, a new clue is unearthed that sends the young detectives to the Honeycomb Caves. After many dangerous encounters, Frank and Joe discover a powerful searchlight in one of the craggy caverns along the seacoast. In the brilliant white glare of the searchlight, the startling secret of the caves is dramatically revealed.

When Mrs. Putney seeks Nancy Drew’s help in recovering her stolen jewelry, the search for the thieves takes the teen-age detective and her friends Bess and George to the colorful French Quarter of New Orleans. But the quest is hampered by the strange behavior of Mrs. Putney, and two young women who are being victimized by so-called spirits. How can Nancy fight these unseen perpetrators of a cruel hoax? And how can she help the gullible victims when the spirits warn them not to have anything to do with Nancy?

With two cases in tow, the Hardy boys look to Turner mill for clues. Determined to learn the secret of the old mill, Frank and Joe employ a clever ruse to gain entrance, only to find themselves trapped. How the young detectives extricate themselves from this dangerous situation and unravel mysteries will keep readers tense with suspense!

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. Clue by clue, Frank and Joe cleverly fit into place the scattered pieces of this dangerous puzzle and come up with the astonishing solution.