The Sinister Signpost
 The Sinister Sign Post (later retitled The Sinister Signpost ) is Volume 15 in the original The Hardy Boys Mystery Stories published by Grosset & Dunlap.This book was written for the Stratemeyer Syndicate by Leslie McFarlane in 1936. 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.