By Franklin W. Dixon
A swish new hydrofoil is scheduled to begin ferrying passengers among Bayport and Cape Cutlass. yet company enemies of the hydrofoil proprietor have stirred up a hornets’ nest of violent competition between small boat proprietors. Fearing sabotage, he begs Frank and Joe Hardy to protect the Flying Express on her maiden journey. Startling advancements plunge the teenage detectives right into a risky chase through sea, air, and land in pursuit of a gang of hardened criminals who function by means of the indicators of the Zodiac. pressure mounts while the Flying exhibit vanishes – and so does Sam Radley, Mr. Hardy’s expert operative. Peril stalks Frank and Joe’s each strikes as they search out the terrifying gangleader Zodiac Zig and his vicious henchmen.