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

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.

Mystery - The Hardy Boys Mystery #45.

The handwritten will of a deceased world-traveler is strange and mysterious. Its cryptic instructions are to deliver “the valuable Aztec warrior to the rightful owner, a descendant of an Aztec warrior.” Frank and Joe Hardy have only one slim clue to work with: the name of a complete stranger who can help. Despite the harassments, the threats, and the attacks made upon them, Frank and Joe unravel clue after clue in their adventure-packed search for the living descendant of the mighty Aztec nation which once ruled in Mexico. It takes as much high courage as clever deduction for the young detectives to defeat their ruthless foes and to decipher the fascinating secrets of the strange and mysterious will.

While the Hardy Boys investigate the theft of valuable antique weather vanes from Pennnsylvania Dutch farms, their father tracks down a Pentagon employee who has stolen a valuable secret.