The turning of the year brought a winter so severe that the Thames froze solid from London Bridge to Blackfriars. It was the second week of January when a matter of urgent medical necessity called me away from my Paddington practice and back into the immediate orbit of my friend at 221B Baker Street. Mary, fully recovered from the terrors of our Boxing Day adventure, had insisted I visit him, noting with her usual sharp perception that Holmes would likely be suffering from the post-holiday reaction that always threatened his brilliant mind when London grew quiet.
When I entered our old sitting-room, I found it enveloped in a dense haze of shag tobacco. Holmes was not languishing, however. He was seated at his chemical table in his purple dressing-gown, surrounded by test-tubes, focusing the beam of an electric torch through a large, raw crystal of blue fluorite.
"Ah, Watson!" he cried without looking up. "You arrive at a highly instructive moment. I am testing the refractive index of various Derbyshire minerals against the known properties of the Morcar sapphire suite. The public may be satisfied with the government’s explanation of the Andaman fund liquidation, but the criminal underbelly of Europe is experiencing a distinct tremor."
"A tremor, Holmes?" I asked, taking my familiar chair by the roaring fire and warming my frozen hands.
"Precisely. Lord Holdhurst’s agents have been quiet, but Herr Oberstein—our naval fence in Hull—is furious. He has realized that the true Blue Carbuncle has escaped his grasp forever. My informants in the East End tell me that Oberstein has invoked a secondary clause in his contract with the late Dr. Mirabeau."
Before I could ask what this clause entailed, the heavy iron knocker downstairs rattled violently. A moment later, Mrs. Hudson conducted a young woman into the room. She was breathless, her expensive woollen cloak dusted with fresh snow, and her face distorted by an expression of pure, unadulterated panic.
"Mr. Holmes!" she gasped, clutching the edge of the mahogany table for support. "You must help me. I am the personal secretary to the Director of the Greenwich Observatory. This morning, when we opened the transit-circle pavilion, we found the Chief Chronometer missing. In its place, stuck into the empty velvet housing with a heavy iron nail..."
She broke off, her breath rattling in her throat as she reached into her pocket. She produced a small object and placed it trembling upon the table.
It was a single goose feather, dyed a brilliant, artificial shade of sapphire blue. Tied to its quill by a piece of tarred hemp twine was a small, brass gear-tooth—the identical signature of the Crewe locomotive works that we had tracked through the Derbyshire snows. The shadow of the Blue Carbuncle had not been laid to rest; it had mutated, striking at the very heart of the nation’s time-keeping establishment on the coldest morning of the New Year.
