Goldsmith, New York, 1931.  Hard cover, 216 pages.  Very good; blue cloth with black lettering on front and spine, spine ends bumped with some bleaching along edges, small dent at top edge of rear board and small bleach spot; binding sound with headbands.  Dust jacket has some edge and cover wear, short tears and small losses, top rear panel edge sunned, spine sunned.  Book interior clean and unmarked with lightly browned pages (not brittle).  Deciphering sheet laid in.  ‘A valuable safe disappears in a strange way.  Perry and his chums in the Skull Mystery Club offer to hunt for it, but when they locate it they find that the real mystery has just begun.  This book takes the reader through many adventures before the secret cipher is interpreted and the perplexing robbery cleared up.’ (from rear panel)