Hidden treasure, sabotage, pirates: It’s just another day in the life of Frank and Joe Hardy, America’s favorite young detectives! In this adventure, the Hardy Boys race to find their missing friend and protect a sensitive naval station from secret attackers. Can the Hardy Boys crack the case before it’s too late? This is a reprint of the 1929 first edition of The Hardy Boys: The Secret of the Caves, without cuts or censorship, as originally written by Leslie McFarlane under the pen name Franklin W. Dixon.