The secret of the caves

The Secret of the Caves (first published in 1929; revised in 1965) is the seventh book in The Hardy Boys mystery series. Frank and Joe Hardy, the teenage detective brothers, become involved in two intertwining cases: the disappearance of a young college professor named Morgan and the strange occurrences surrounding Honeycomb Caves, a mysterious coastal area near Bayport. When their friend Chet Mor...