This was the eleventh Hardy Boys mystery novel, first published by Grosset & Dunlap in 1932 and written by the wonderful Leslie McFarlane under the Stratemeyer Syndicate house pseudonym Franklin W. Dixon. The first thirty-eight books in the series were "revised" under the direction of Stratemeyer's daughter Harriet Adams between 1959 and 1973, which resulted in completely different books having the same title and author name. The newer books were, as a rule, shorter, simpler, and suitable for a younger reader than the originals. I've been reading some of the original and newer editions back-to-back to compare them, and, while I still prefer the old novel, this one written by James Buechler and published in 1962 is the best I've found yet of the newer versions. The original book had 213 pages and 24 chapters, and the new one was 174 pages long (with several interior illustrations) and 20 chapters. The plot of this one follows the original plot closely than others I've read, which may account for my opinion. The 1962 novel condenses two criminal gangs into one, exchanges stolen jade for the theft of a stamp collection, and introduces several characters as friends of the Hardys who don't appear in the original. (Though the girlfriends of Frank and Joe, Callie Shaw and Iola Morton, don't get much in the way of character development beyond the fact that we're told that they're both pretty. -sigh-) The Hardy parents are away on vacation at the start of the story, and Aunt Gertrude is looking after them. A banker comes to see Mr. Hardy about some threats he's received, but Frank and Joe convince him to let them take on the case. It's a true locked-room mystery, as threatening notes have been left in a room sealed with a time-lock. The local police are treated with a lot more respect in the revised version, but Aunt Gertrude's role has been shortened and watered-down considerably. The biggest difference (do you need a spoiler warning for a kids' book from ninety years ago? Very well, this is it!) is that in the original, a criminal madman falls to his death from a rooftop, while in the new one he's forgiven and rehabilitated and the Hardys and their pals have a big surprise party. I found both versions to be fun reads but would recommend the original to kids on a more advanced reading level and the more recent to beginners.