The complete audiobook is available for purchase at Audible.com:
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The Secret of the Caves
By Franklin W. Dixon
Narrated by Gary D. MacFadden
The Secret of the Caves is the seventh novel in The Hardy Boys mystery stories series.
At their home in Bayport Frank and Joe and Fenton, receive a visitor who informs them that Professor Morgan Todd from Kenworthy College has disapperared. At the time Fenton is working on security for a coastal radar station, which is under construction. The boys visit the college and are informed that the professor is away in Europe. However, the boys become suspicious, and their investigations lead them to Honeycomb Caves in Rockaway, where they uncover a plot to disrupt the operation of the radar station.
