The one with The Hoxton Creeper, played by tragic agromegaly-sufferer Rondo Hatton. They build up the suspense by showing him in silhouette right up until the last few minutes of the film when Conover craves a boon of him, namely would he mind awfully snapping Holmes's back (Lumbar region, third vertebrae)? Of course he doesn't succeed but his grand entrance doesn't disappoint. Otherwise it's a pretty good story about crims on a hunt for the pearl of the title, hidden in one of several busts of Napoleon, and efficiently done. However, Watson and Lestrade are particularly dumb in this one. You wonder how Holmes restrains himself from delivering a torrent of verbal abuse sometimes. It also contains one of my favourite lines from the series: as Holmes sits down gingerly and starts removing his latest disguise, he says "Oh, I'm as stiff as a varnished eel!"