Reluctantly, Sherlock Holmes agrees to assist Inspector Lestrade who is being hounded by an obnoxious nobleman whose jewel-encrusted dagger has gone missing. However, what Holmes initially believes to be a simple theft turns out instead to be his first encounter with a master criminal, who is as ruthless as he is brilliant, and whom Watson dubs The Merchant of Menace.Soon Holmes finds himself matching wits with a man who will steal anything if the price is right. Moreover, this thief will go to any lengths, including blackmail and murder, to achieve his desired goal.As Holmes comes to understand his adversary, he also begins to realize he can only react to the Merchant because he has no idea where this criminal mastermind will strike next.