"Keep low, keep your pack tight to your ribs, and for heaven's sake, do not touch the keystone," Imani whispered, her voice barely carrying over the muffled thrum of heavy rotary drills vibrating through the bedrock behind them.
Teo nodded, though his knuckles were already white against his flashlight casing. "Right behind you. Low and smooth like silt."
Imani slid onto her stomach, the damp stone instantly biting through the canvas of her field trousers. The crawlspace was a claustrophobic nightmare of jagged limestone teeth, suspended in a delicate equilibrium created by the cave-in. Above her spine, a four-ton slab of sedimentary rock hung by a sheer lip of calcite. Every vibration from Vance's heavy machinery transmitted through the rock face like the steady, ominous heartbeat of an encroaching beast.
She wriggled forward using her elbows and toes, measuring each breath so her chest wouldn't scrape the hanging ceiling. Halfway through the twenty-meter squeeze, the air grew noticeably warmer, carrying the rich, alkaline scent of ancient mortar and sealed bronze. They were close. The vault's true antechamber lay just on the other side of this choke point.
Then, the mountain shuddered.
A deep, thunderous boom reverberated through the stratum—Vance had set off a secondary seismic charge on the outer shelf, far closer than anticipated. Dust rained down in blinding sheets. The ceiling slab groaned, dropping two inches with a sickening crunch of grinding grit.
"Imani, move!" Teo shouted from behind her.
"Don't rush it!" she barked back, but the instinct of panic had already seized him. Teo surged forward, his bulky field pack catching the corner of a fractured support pillar. The stone splintered. With a sharp crack like a rifle shot, a shower of rubble gave way above them.
Imani lunged forward, clearing the aperture and tumbling into open air just as the ceiling collapsed behind her. She spun around immediately, heart in her throat, screaming Teo's name through the billowing cloud of chalky dust.
"I'm here! I'm—gah!" A sharp gasp of pain cut through the haze.
She scrambled to the mouth of the debris pile. Teo had made it through the narrowest throat of the gap, but his lower half was wedged under a fallen crossbeam of shale. Worse, their primary multi-spectrum prism lamp—the specialized optic tool required to calibrate the hidden chromatic locks of the Tomorrow People—lay flattened beneath a jagged block, its crystal lenses crushed into glittering sand.
"Easy, don't thrash," Imani said, her voice dropping into the calm, measured register she reserved for trench collapses and snakebites. She set her crowbar beneath the shale crossbeam, finding a fulcrum against solid floor stone. "On three, pull your leg back. One. Two. Three!"
She threw her full forty-five years of muscle and leverage onto the bar. The beam shifted just enough. Teo dragged himself free with a sharp hiss of agony, rolling onto his back and clutching his right wrist and left ankle. The boot leather was torn, and his ankle was already swelling violently against the cuff, while his dominant wrist hung at an awkward, sprained angle.
"The prism lamp," Teo gasped, sweat cutting tracks through the gray dust on his forehead. "Imani, I crushed the lamp. We can't read the chromatic refractive index without it."
"The lamp is gear. Gear is replaceable," Imani said firmly, kneeling beside him to wrap a tight compression bandage around his throbbing ankle before splinting his wrist with two aluminum tent stakes. "You are not. Breathe, Teo. We're in."
She clicked on her backup halogen torch and swept the beam across the vast room they now occupied. The breath caught in her chest.
They had breached the Hall of Testament. Towering twelve meters above them was a semicircular amphitheater carved from black diorite. The walls were entirely covered in a colossal, continuous bas-relief mural, framed by three concentric rings of rotating bronze glyph dials. Unlike any early civilization on record, this mural did not glorify kings or conquerors. It was a staggering visual encyclopedia: star charts depicting precession cycles spanning ten thousand years, cross-sections of botanical seed banks, and intricate anatomical drawings.
At the center of the mural stood a sealed circular portal, surrounded by twelve interlocking dial segments. Without their prism lamp to reveal the subtle color-coded wavelengths baked into the pigment, the dials had to be aligned manually through the linguistic cipher etched along the outer frieze.
Teo dragged himself up against the base of the dial pedestal, squinting at the dense rows of logograms. "It's a conditional syntax," he murmured, his teeth chattering from the shock of the injury. "'When the northern eye closes, turn the third wheel to the root of the grain.' But the dialect uses dual-aspect verbs. If I misread the tense, the locking pins will shear off permanently."
From beyond the collapsed corridor, the high-pitched shriek of Vance's diamond-tipped bore began vibrating through the stone. Vance was less than thirty minutes from punching through the rubble.
"My head is pounding, but I know this grammar, Imani," Teo insisted, his eyes wild with adrenaline and pain. "I can translate the direct sequence right now and turn the dials. Give me ten minutes."
Imani examined his dilated pupils and the slight tremor in his splinted hands. A single mistranslation of the ancient dialect would trigger the vault's fail-safe, sealing the repository forever. Alternatively, she still had their low-frequency satellite transceiver. If she climbed the air flue near the ceiling, she could patch a high-resolution photograph of the cipher back to Nnamdi at base camp to run against their digital lexical database. It would take twenty-five minutes—giving Vance precious time to catch up—but it would eliminate the risk of a catastrophic translation error.
The floor hummed beneath their boots as Vance's drill ground deeper.