"When we arrived at St. James's Square, your assailant was lying face down on the pavement. He was still clutching a cargo hook, the kind used by longshoremen."
"So that was it," Holmes murmured so that his voice wouldn't quiver. "I assumed it was a knife." A hook would have sliced him open just as easily as any blade... Perhaps Smee had thought it poetic justice?
Lestrade brought out his notebook and showed Holmes a rough pencil sketch of the tableau. "His head had been mutilated by an expanded revolver bullet. It entered dead centre in the back of his skull, exiting through the forehead. I know it wasn't you," he added hastily. "Wiggins told me. He said he arrived while Smee still had you pinned against the railings, and that you said something in an odd voice which made the man lower his weapon and step backwards, just before... well, just before he was killed. Do you remember hearing a shot being fired at all, or seeing anyone else on the street?"
"I don't... think so..." Holmes was now very glad he hadn't eaten anything back at the flat.
"Well, that's interesting... because Wiggins was certain he didn't see or hear anything of the sort, either."
"Ah!" Of course there hadn't been! "Tell me, Inspector, have you ever heard of a man called Von Herder?"
"Von Herder... No, but something tells me I'm about to. German, is he?"
"Was. A blind mechanic, commissioned by Moriarty to construct an air-gun." Holmes jumped up and began to pace. "I knew it existed, but I never got the chance to handle it. A truly unique design: silent, deadly, and tremendously powerful!"
"And... don't tell me, let me guess," Lestrade sighed. "It fires revolver bullets, like the one we found."
"Exactly! And if you were to examine the chimney on the roof where we were hiding, you would no doubt find a similar projectile buried in the brickwork."
"So that's why we didn't hear a shot! It didn't even occur to me... Hold on, you say that gun was commissioned for the Professor? Then... were both those shots actually meant for you?"
Holmes shook his head. "I should say rather that Moriarty had the gun commissioned for the use of one of his agents: Colonel Moran."
Lestrade nodded grimly. "I remember that name. Isn't he Moriarty's chief of staff?"
"Indeed, and a crack shot with a rifle. I promise you, Inspector, if Moran had intended a bullet for either one of us, we wouldn't be here to discuss it now."
"So the Colonel saved you from Smee before he could gut you... Sorry. And then... bloody hell, he deliberately drove us off the roof!"
"In fairness, Moran must have been watching us for some time while getting a clear shot. He would have seen there was a strong chance that neither of us would be plummeting to our deaths." Moriarty really didn't want any harm coming to his opponent, did he? At least for now...
"Kind of him, I'm sure!" Lestrade snorted.
And the second shot had likely been intended to drive the fugitives towards Baker Street... but why? Moriarty must have known that returning to the flat would probably help to restore Holmes's memory, so what the devil was the man playing at?
"Damned if I know!" Holmes only realised he'd been thinking aloud when Lestrade answered, the Inspector wearily massaging his forehead as if fighting off a headache. "Who can fathom the mind of an evil genius?"
"Well, it looks as if I haven't got much of a choice, have I?" Holmes retorted sharply. " 'Your presence is required...' I do hope you and the rest of the force have some idea of where that might be, because I haven't the least notion!"
"We'll find them," Lestrade stubbornly maintained. "We've got constables swarming all over Mycroft's rooms, and the house behind. I have to say, Moriarty having his agents tunnel between the two was pretty bloody cunning."
"It was a piece of bloody effrontery!" Holmes snapped. "Remember the Red-Headed League? The gold heist from the Coburg Bank? Moriarty used this tunnel as payback for the other! He's mocking me, damn him!"
Lestrade looked hard at Holmes. "You're certain? Why didn't you mention that before?"
"I didn't understand it until just now!" Holmes almost wailed. "I can barely recall even meeting the man, for God's sake – what do you want from me?"
"I want you to come back with me to Pall Mall, is what!" Lestrade was already halfway into his coat. "Come on, wrap up, we've a crime scene to visit!"
The detective didn't need telling twice, grabbing his coat off the back of his chair and wishing for the first time that he'd thought to bring a hat. "Not that I'm complaining, but what happened to not interfering with any new evidence?"
"You won't be," Lestrade said sternly, "but I can't see any harm in you casting a fresh eye over what we've got, at least. Hopkins was right, you just might see something everyone else missed. At least now we know Moriarty wants you to find him! And I wish to God that made me feel better," he muttered grimly, leading the way out of the office.
Holmes chose not to reply. He didn't feel especially hopeful about it, either.