One of the most famous of the "lost" tales scattered throughout Watson's stories, a fair few have tried to realize this intriguing sounding tale. The ones I've read are of varying readability but this, I think , is the best I've read yet. It makes sense and without bringing Dr. Morou (which I swear I've seen/heard done) in or another bizarre explanation.
Richard L. Boyer does a fine job of channeling Watson in this text and I felt I was actually seeing Holmes and Watson. His Holmes in particular is that odd mixture of sympathy and arrogance, understanding and maddening inability to tell anyone anything.