The Secret of Pirates' Hill is Volume 36 in the original The Hardy Boys Mystery Stories published by Grosset & Dunlap. This book was written for the Stratemeyer Syndicate by John Almquist in 1956. 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 shortened in 1972 by Priscilla Baker-Carr resulting in two slightly different stories sharing the same title. Source: Wikipedia (en)