The Hardy Boys: The Secret of the Caves (Book 7)

The Secret of the Caves is Volume 7 in the original Hardy Boys series of mystery books for children and teens published by Grosset & Dunlap.

This book was written by Leslie McFarlane in 1929 for the Stratemeyer Syndicate, which published it under the pseudonym Franklin W. Dixon.

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.

The Hardy boys travel to Kenworthy College and meet Todd's colleague, Cadmus Quill. A clue leads them to Rockaway, but when it is mentioned they notice strange behavior from Cadmus Quill. While driving to Rockaway they hear a radio report that the radar station has been damaged, so they instead return to Bayport. Their help is not needed so they leave for Rockaway, stopping at Palais Paris to purchase a spinning wheel for their Aunt Gertrude. When they stop in at Tuttle's General Store Mr. Tuttle warns them to keep away from Honeycomb Caves because people have seen strange lights and heard shooting coming from the caves. Instead of leaving, the boys decide to camp at Honeycomb Caves with their friends Chet and Biff.