#7 in the series. Grosset and Dunlap picture cover book. Author was Leslie McFarlane writing under the house pseudonym "Franklin W. Dixon." Cover art by Rudy Nappi. Original copyright 1929. New copyright 1964, with revised text very different from the original story. This is the revised text. Rewritten by Andrew E. Svenson, for the purpose stated on the copyright page of other revised texts: "In this new story, based on the original of the same title, Mr. Dixon has incorporated the most up-to-date methods used by police and private detectives." Print run 1964, Carpentieri-coded 1964C-58. Rear cover lists to The Mystery of the Aztec Warrior (1964) and the Detective Handbook (1959), and the last title of the internal list is The Viking Symbol Mystery (1963). Excellent, clean, square book with very good spine. Almost no corner bumping but the spine top and bottom do have light edgewear. Black/white multi-scene endpapers. A small typed ownership label on the front pasted-down endpaper. No other writing/markings. HBC7