The sulfurous smoke from the overturned brazier filled the chamber with a blinding, toxic fog. Through the haze, the flash of the bodyguard's revolver illuminated the rock walls in violent, jagged bursts. The roar of the gunshot was deafening in the enclosed cavern, followed instantly by the sharp whine of a bullet ricocheting off the limestone mere inches from my head.
"Watson! Low!" Holmes’s voice barked through the gloom.
I dropped to my knees on the icy stone floor just as a massive shape lunged through the darkness. It was the scarred bodyguard. Deprived of his lantern, he was using his brute bulk as a weapon, throwing himself blindly toward the flash of our firearms. He collided with me like a runaway dray horse, sending my revolver skittering away into the blackness. Thick, calloused fingers locked around my throat, cutting off my breath, while the smell of cheap gin and damp wool overwhelmed my senses.
I choked, striking upward with my fists, but the man’s muscles were like iron. Suddenly, a brilliant, focused beam of light pierced the smoke. Holmes had shuttered his dark lantern and struck the brute across the temple with its heavy brass casing. The bodyguard groaned, his grip loosening as he collapsed sideways onto the stone flagstones, unconscious.
"Quickly, Watson, the others!" Holmes cried, pulling me to my feet.
He swung the lantern beam across the chamber. The telegraph table was overturned, and the brass key lay crushed beneath a boot print. Of Lord Blackwood and Dr. Mirabeau, there was no sign. But the beam of light caught a frantic movement at the rear of the cavern, where a narrow, iron-runged ladder climbed vertically up the sheer face of the rock chimney.
"They are ascending to the surface," Holmes said, his voice taut with urgency. "If they reach the snow drifts above Mam Tor, they will vanish into the mountain passes."
We rushed to the foot of the chimney, but before Holmes could set his foot on the first iron rung, an ominous, deep-toned rumble echoed from the depths of the mountain. It was not the sound of gunfire, but the terrible, grinding roar of shifting earth. The heat from the overturned brazier, combined with the concussive blasts of the revolvers, had fractured a delicate ice-dam in the upper limestone channels.
"The meltwater, Holmes!" I shouted over the rising din.
A torrent of freezing, black water suddenly erupted from the mouth of the chimney above. It poured down the vertical shaft like a cataracts, extinguishing our lantern and slamming into us with bone-shattering force. The cavern floor began to flood instantly, the dark water rising rapidly around our ankles, choked with jagged blocks of ice and loose debris.
In the absolute darkness, drenched to the skin and shivering violently, I felt Holmes grab my shoulder. "The underground river, Watson!" he shouted through the roar of the deluge. "The water is draining toward the main Speedwell channel. We must swim with the current, or we will be drowned in this vault like rats in a cistern!"
Clinging together against the furious rush of the freezing tide, we threw ourselves into the black, swirling waters of the subterranean stream, carried blindly into the unknown depths of the Derbyshire peaks.
