First Edition. E. C. Caswell dustjacket art and illustrations. Novel of a sixteen year old boy who takes over an old copper mine and introduces mushroom farming into the tunnels. "Suffice to say that there is mystery and suspense a plenty, including startling events at the mine, a narrow escape or two, a hot pursuit across a river followed by an automobile chase, and finally the snatching of success from seemingly inevitable failure in Marty's big undertaking." Near Fine but for foxing at page edges and innocuous previous owner stamp exhorting borrowers to return book after 5 days at front pastedown and front endpaper, in attractive Very Good plus dustjacket, mild wear.