Marcus sealed the seismic array detonator control at 04:42 in the morning, Nevada time. The decision to use the mercenaries' own equipment against them was made in the ninety seconds after Commander Harrow's team had begun evacuating their gear toward the surface access shaft—the one they had drilled, not the one Marcus had originally used.
The seismic array included a controlled implosion circuit, designed for precisely the operation Marcus intended: a directed collapse of a geological section to seal a specific passage.
If he fired the implosion circuit at the junction of the vault door corridor and the primary cavern access passage, he would collapse approximately forty meters of tunnel, creating a rubble seal that would take industrial drilling equipment weeks to clear—enough time for a federal protection order to be filed, reviewed, and granted. Commander Harrow had not been told he intended to do this.
Talon stood beside Marcus at the control station while Reyes and Patel finished copying the last data drive to the survey backup unit—a redundant hardware precaution that had been Reyes's insistence from the first day of the expedition and was now one of the most important decisions of their professional lives.
"Ready," Reyes said.
Marcus fired the implosion circuit. The sound was different from the mercenaries' seismic charges—compressed rather than expansive, a deep internal thump that the tunnel walls absorbed rather than amplified. Forty meters behind them, they heard the rubble cascade as the passage section collapsed.
Sealed.
"We need to surface before the magma surge reaches this level," Patel said, already moving toward the mercenaries' access shaft at the far end of the corridor.
Marcus looked at Talon. The raptor had moved to the sealed section of collapsed tunnel and was pressing one foreleg flat against the rubble, its echolocation pulse directed into the debris at low frequency. Reading what was on the other side.
Marcus checked his sensor. The lower passages were still there, beyond the rubble—sealed from human intrusion, but intact. The magma surge had flooded the lowest levels but had not reached the geothermal oasis chambers where the preserved ecosystem lived. The collapse had redirected the surge pressure into a side channel that Patel's geological sensors had identified as a pressure relief vent.
The oasis was still there. The ecosystem had survived. Talon withdrew his foreleg from the rubble and turned to Marcus. The amber-gold eyes held the same quality Marcus had first observed when they met: not the blank animal stare of a creature without cognition, but the directed, evaluating gaze of an intelligence assessing a situation.
The raptor clicked twice—the move forward signal—and turned toward the surface shaft. Marcus followed. The climb was long and hard and they emerged onto the Ash Ridge Badlands at dawn, dust-covered and exhausted, into an air that tasted of cold desert morning and was, after the sustained geothermal heat of the underground, almost shockingly cold.
Talon stepped out of the surface shaft opening and stopped. He had never been at the surface before. The sky—vast, blue-gray, edged with the first gold of sunrise—was something his sixty-five-million-year lineage had not seen.
The raptor stood completely still for a full minute, his echolocation pulse quiet, his amber-gold eyes moving slowly across the horizon. Then he looked back down the shaft. Home.