The secret of the caves

"The Secret of the Caves" by Franklin W. Dixon is a mystery novel written in 1929. When teenager Morgan Todd disappears, Frank and Joe Hardy team up with their detective father to find him while protecting a coastal radar station from sabotage. Their investigation leads them to mysterious Honeycomb Caves, where strange lights flicker and gunshots echo. As the brothers and their friends camp near the caves, they encounter a hostile hermit, unexplained explosions, and arson. The young detectives must unravel the connection between the missing man and sinister activities threatening national security.

The secret of the caves, by Franklin W. Dixon. Republished by OpenStories from Project Gutenberg eBook #75310.