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

The Hardy brothers are called in to investigate when the ATAC hears that a major college football team is about to throw a championship game. Everyone from the star quarterback to the coach are in play as suspects, and the clock is running out for Frank and Joe to score another mission touchdown.

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.

Titles include "Webster's New World Dictionary, Webster's New World Thesaurus" and "Words Most Often Misspelled and Mispronounced".

To their friends’ envy, Biff and Chet plan to take a boating vacation up the coast. The joy of sending them off soon turns to anxiety as neither of them make contact with home for several days. Convinced that something’s happened to them, the Hardy boys and their friends go on a search filled with adventure and peril in hopes of retrieving their missing chums. This is the fourth book of the Hardy boys series, first published in 1928. While the author is credited to be Franklin W. Dixon, in reality, Leslie MacFarlane and Edward Stratemeyer are primarily responsible for the early volumes, including this one. This Standard Ebooks edition is based on the original 1928 text. This book is part of the Standard Ebooks project, which produces free public domain ebooks.

Teenage detectives Frank and Joe Hardy investigate a case of counterfeiting.