__WIKIA_BANNER__ The Secret of the Caves is the seventh book in The Hardy Boys series. It was first published in 1929 by Grosset & Dunlap, and revised re-released in 1964. The book begins with Chet Morton showing off his new metal detector to the Hardy boys and Biff Hooper while inviting them to camp at Honeycomb Caves. Meanwhile, their father, Fenton Hardy, is working to protect a Coastal Radar Station from sabotage during its construction. They are interrupted by Mary Todd who tells them that her brother, Morgan Todd, is missing and asks Fenton to find him. The Hardy boys and their father decide to team up to both find Morgan Todd and protect the Coastal Radar Station.