The Secret Warning (Hardy Boys, Book 17)

Blurb

The Secret Warning is Volume 17 in the original The Hardy Boys Mystery Stories published by Grosset & Dunlap.
This book was written for the Stratemeyer Syndicate in collaboration by John Button and Leslie McFarlane in 1938. Between 1959 and 1973 the first 38 volumes of this series were systematically revised as part of a project directed by Harriet Adams, Edward Stratemeyer's daughter. The original version of this book was rewritten in 1966 by James D. Lawrence resulting in two different stories with the same title.