Holmes’s face went ashen. “Dynamite,” he breathed. “And picric acid. The ticking of the clocks masked the sound of a chemical clock. The Professor knew he was being watched. He built ‘The Mourner’ to encode the time of detonation.”
The cycle repeated every thirty seconds.
I, Dr. John Watson, set down my pen. “My dear Holmes, the ‘Tottenham Court Road Strangler’ is hardly commonplace. The papers say—”
His hands, those long, artistic hands, became a blur of precise, terrifying action. He disconnected a vial, steadied a piston with a paperclip from my pocket, and used a fragment of his own shoelace to bind a leaking seal.
Holmes rose, dusted his knees, and adjusted his cravat. He looked at Eleanor, then at me. The languid, theatrical mask was back in place, but beneath it, I saw the steel.
Holmes moved through the rooms like a bloodhound, his long fingers trailing over mantelpieces, his nose twitching. He paused before the locked door of the Professor’s study.
Then, a tiny, hidden door on the watch face swung open, and a minuscule figure—a silver mourner in a widow’s weeds—emerged. It beat its tiny chest, raised a microscopic hand to its forehead, and then sank back into the mechanism.