A sleek new hydrofoil is scheduled to start ferrying passengers between Bayport and Cape Cutlass. But business enemies of the hydrofoil owner have stirred up a hornets nest of violent opposition among small boat owners. Fearing sabotage, he begs Frank and Joe Hardy to guard the Flying Express on her maiden trip. Startling developments plunge the teenage detectives into a dangerous chase by sea, air, and land in pursuit of a gang of hardened criminals who operate by the signs of the Zodiac. Tension mounts when the Flying Express vanishes and so does Sam Radley, Mr. Hardys skilled operative. Peril stalks Frank and Joes every moves as they hunt down the terrifying gangleader Zodiac Zig and his vicious henchmen.
Franklin W. Dixon is a pen name used by a variety of authors writing for the classic series, The Hardy Boys. The first and most well-known "Franklin W. Dixon" was Leslie McFarlane, a Canadian author who contributed 19 of the first 25 books in the series. Other writers who have adopted the pseudonym include Christopher Lampton, John Button, Amy McFarlane, and Harriet Stratemeyer Adams.