That's Watson's cane. Had the realization not frozen every muscle in his body, Sherlock Holmes might have been able to interfere with Lord Blackwood's abrupt dismissal of Irene Adler's best efforts. The metalshod tip of the cane was pointed at her throat before his brain had even begun to start cataloging all the possible ways in which Blackwood might have acquired that most intimate of all John Watson's accoutrements. Irene recognized it too, and the pleading farewell she sent him with her eyes was mixed with a comprehending pity. He raised a hand, his protest hanging in the air.
"No!"
