The secret of the caves / Dixon, Franklin W

Young detectives Frank and Joe Hardy, investigating the disappearance of a professor, encounter a hot-tempered hermit, and sabotage at the radar station and Honeycomb Caves.

Frank and Joe solve a mystery involving the disappearance of a professor, a hot-tempered hermit, sabotage at the new Bayport Coastal Radar Station, and the Honeycomb Caves.

When the Hardy boys reached the caves, they came unexpectedly upon a queer old hermit.

Frank and Joe solve a mystery involving the disappearance of a professor, a hot-tempered hermit, sabotage at the new Bayport Coastal Radar Station, and the Honeycomb Caves.