The sensation of the icy current rushing over my head was terrifying. Wrapped in absolute, impenetrable darkness, I was swept along by the subterranean deluge, my limbs turning numb within seconds from the biting frost of the mountain water. I fought desperately to keep my chin above the swirling torrent, gasping for air in the rare, suffocating pockets of space between the water’s surface and the low limestone ceiling. Just as my strength began to fail entirely, a powerful grip seized the collar of my heavy woollen coat.
With a final, desperate heave, Holmes dragged me out of the main current and onto a shelving beach of smooth, wet shingle. I lay there for several minutes, coughing up the bitter, metallic-tasting water, shivering so violently that my teeth clicked together like castanets.
"Steady, Watson, steady," Holmes panted beside me.
A sudden, warm spark flickered in the darkness. Holmes had produced his waterproof matchcase—a preventative measure he never neglected on our winter excursions. He struck a match, and the tiny, brilliant sulfur flame revealed his face, pale and streaked with black soot, but his eyes were alive with an almost manic intensity. He quickly located a dry piece of drift-wood left behind by an older flood and kindled a small, smoky fire.
"Where are we, Holmes?" I managed to ask, crowding close to the meager warmth.
"We have been carried nearly a quarter of a mile through the limestone spine," Holmes replied, using the firelight to examine his pocket compass. "If my calculations of the Castleton topography are correct, we are currently standing in the lower basin of the great Peak Cavern, directly beneath the foundations of Peveril Castle. But look here, Watson. We are not the first to seek refuge on this subterranean shore."
He held up the burning piece of drift-wood, casting its light toward the far wall of the chamber. There, resting on a flat boulder just above the water line, was a heavy, oiled leather Gladstone bag. It was completely dry.
Holmes sprang forward, his long fingers instantly working the brass clasps. As the bag fell open, the reflection of our small fire was completely eclipsed by a cold, hypnotic radiance. Resting inside, nestled on a bed of dark velvet, was the complete Mogok collection. There were the brilliant crimson rubies from the Surrey safes, the original Blue Carbuncle retrieved from London, and its massive, star-lit sapphire twin.
"They abandoned the weight when the flood hit the chimney," I whispered, awestruck by the sight of the treasures united at last.
"Or rather, Dr. Mirabeau intended to double-cross his aristocratic employer," Holmes corrected, pointing to a small, hand-written ticket attached to the velvet lining. It bore a single name and an address: Herr Oberstein, The Minories, Hull.
"The great international spy and naval fence," I gasped. "The gems were to finance the purchase of the stolen submarine blueprints!"
"Precisely," Holmes said, his voice tightening. "Lord Blackwood was merely the aristocratic dupe, providing the capital for Lynch and Mirabeau to extract the stones. But the shadow of the Blue Carbuncle is long, Watson. Mirabeau is a desperate man. He knows the stones are here, and he knows there is only one viable exit from this lower cavern that remains unblocked by the ice."
Holmes snapped the bag shut and drew his pocket-knife, his eyes fixing on the narrow, ascending rock fissure that led toward the surface. "The storm outside has ceased, but the final trap is about to spring. Come, Watson, let us welcome the New Year by returning these stones to the light of day."
