The tunnel didn't end; it evolved.
The rough limestone of the Chicago bedrock gave way to something smoother, paler, and infinitely older. The air grew warm and humid, smelling of salt and prehistoric dust.
"Stop," Isobel whispered, raising a hand.
Jax skidded to a halt, his flashlight beam cutting through the gloom. They were standing on a ledge overlooking a vast, subterranean amphitheater. The ceiling was lost in darkness, but the floor...
The floor was a graveyard.
Massive, calcified ribs curved up from the ground like the arches of a gothic cathedral. Spiraling ammonites the size of tractor tires were embedded in the walls. This wasn't just geology; it was a fossilized coral reef from a time when the Midwest was a shallow, tropical sea.
"The Bone Orchard," Silas rumbled, scanning the cavern with thermal optics. "I thought this was just a geological theory. The compression layers here should be crushing us."
"The magic holds the roof up," Isobel said, walking forward. She touched a pillar that looked suspiciously like a giant femur. "The Heart beats, and the earth listens."
THUMP.
The vibration was physical now. It rattled the loose stones at their feet. It felt like standing inside a bass drum.
"We need to cross," Jax said, pointing his light across the cavern.
In the center of the Bone Orchard, rising from a lake of luminescent blue liquid, was a spire of crystal. It pulsed in time with the beat. It was raw, unrefined, and terrifyingly beautiful.
The Chicago Heart.
"That's it," Jax breathed. "The battery to end all batteries."
"We are exposed here," Silas warned, checking his six. "The terrain offers zero cover."
"We don't have a choice," Jax said. "My internal clock says we have about ten minutes before those Greyhawks turn us into hood ornaments."
They moved out, stepping carefully over the uneven ground of fossilized life. The blue light from the central lake cast long, skeletal shadows that seemed to dance with every pulse of the Heart.
They made it halfway across the orchard when the silence broke.
ZZZT-CRACK.
A projectile slammed into the calcified rib Jax was using for cover. It didn't ricochet; it released a cloud of heavy, grey gas.
"Contact!" Silas roared.
He shoved Jax down just as a second slug whistled through the air where his head had been.
High above them, on the ridge they had just descended, three silhouettes appeared. The Greyhawks had arrived.
"Stroud, suppress!" Kaelen's amplified voice echoed through the cavern. "Vesper, flush them out!"
The heavy gunner, Stroud, opened fire with his rotary cannon. A hail of Null-slugs rained down on the Bone Orchard. Every impact released a pocket of Normalcy, turning the magical, luminescent fossils into dull, brittle grey stone that crumbled instantly.
"They're destroying the supports!" Silas yelled, huddled behind a massive trilobite shell. "If they neutralize the fossils, the roof comes down!"
"I'm on it!" Jax yelled.
He didn't run away; he ran sideways. He tapped into the tiny reserve of power he'd stolen from the rat-cable. It wasn't enough for a lightning bolt, but it was enough for speed.
Jax blurred, dashing from cover to cover, drawing Stroud's fire.
"Over here, ugly!" Jax shouted, vaulting over a petrified log.
While Stroud tracked Jax, a shadow detached itself from the ceiling.
Vesper dropped. She didn't use a rope; she used gravity boots that allowed her to cling to the stone. She landed silently ten feet behind Isobel.
Vesper drew her anti-magic batons, spinning them. "End of the line, witch."
Isobel turned. She didn't look afraid. In this place, surrounded by millions of years of death, she looked regal.
"You are standing in a tomb," Isobel whispered, her eyes turning pitch black. "Show some respect."
Vesper lunged.
Isobel didn't dodge. She slammed her hand onto the fossilized ground.
"RISE."
She didn't raise a ghost. She raised the memory of the reef.
Sharp, jagged spears of coral erupted from the ground at Vesper's feet. The mercenary backflipped, barely avoiding impalement. The coral slashed her armor, sparking against the carbon fiber.
"Target is manipulating the terrain!" Vesper shouted into her comms. "Standard dampeners ineffective! The environment is too saturated!"
Silas saw his opening. While Vesper was dancing with the coral, Kaelen—the leader—was sprinting down the slope, heading straight for the Heart.
"He intends to bomb the Nexus," Silas realized. "If he drops a Null-grenade into that lake, it will kill the city instantly."
"I cannot stop him!" Isobel yelled, holding off Vesper with a wall of bone shards. "Silas, go!"
Silas looked at his frozen knee. He looked at the distance. He couldn't outrun Kaelen.
"Physics," Silas muttered to himself. "Mass times acceleration."
He reached into his pack and pulled out the canister of alchemical accelerant he used for the Mule's engine. He jammed it into the exhaust port on his suit's back.
"Override safety limits," Silas commanded his suit. "Route all power to servos."
WARNING: STRUCTURAL FAILURE IMMINENT.
"Do it."
The copper wiring on Silas's suit didn't just glow; it turned liquid white. Steam screamed from his vents.
Silas launched himself.
He didn't run; he bulldozed. The sudden burst of hydraulic power propelled his massive frame forward like a cannonball. He smashed through a pillar of limestone, ignoring the debris, intercepting Kaelen's path.
Kaelen saw the metal giant coming. He raised his serrated blade.
"Too slow, Alchemist."
Kaelen side-stepped, slashing at Silas's exposed neck.
Silas didn't try to block. He caught the blade with his tungsten hand. The serrated edge bit deep into the metal palm, sparks flying.
"I am not trying to hit you," Silas growled, the heat from his suit distorting the air. "I am simply the wall."
Silas clamped his hand shut, trapping the blade. With his other hand, he grabbed Kaelen's chest plate.
"Burn."
Silas dumped his entire alchemical heat reserve into his grip.
Kaelen screamed as his suit's temperature sensors redlined. The matte-grey armor began to glow cherry red. The intense heat fried the Null-circuitry inside the chest plate.
Kaelen kicked Silas in the knee—the damaged one.
CRACK.
Silas's leg buckled. He fell, releasing Kaelen.
Kaelen stumbled back, his chest armor smoking and fused. He looked at the Spire of the Heart, only fifty yards away. He pulled the Null-grenade from his belt.
"Mission priority," Kaelen wheezed. He armed the grenade.
"Jax!" Silas roared from the ground. "Catch!"
Jax was fifty feet away, pinned down by Stroud's cannon fire. He heard Silas. He saw the grenade in Kaelen's hand.
He couldn't reach it. He was too far.
But he didn't need to reach Kaelen. He just needed to reach something else.
Jax looked at the heavy Null-slug whizzing past his ear.
"Time to switch lanes," Jax gritted out.
He focused on the bullet. It was moving fast—kinetic energy incarnate.
Jax reached out with his mind and swapped places with the bullet mid-air.
POP.
Jax vanished. He reappeared instantly in the air, right in the path of Stroud's fire, but significantly closer to Kaelen.
Gravity took hold. As Jax fell, he reached out with his remaining spark. He didn't aim for the grenade. He aimed for Kaelen's magnetized gravity boots.
"Opposite polarity!" Jax yelled.
He hit the boots with a magnetic pulse.
Kaelen's feet were suddenly repelled from the ground with violent force. He flipped backward, losing his balance.
The grenade slipped from his fingers.
It didn't fall into the lake. It tumbled onto the stone floor, ten feet from the water.
"Take cover!" Kaelen screamed, diving behind a ridge.
THWUMP.
The grenade detonated.
A sphere of grey silence expanded. It hit the edge of the blue lake.
Matter met Anti-Matter. Magic met Void.
The reaction wasn't an explosion. It was a scream. The Crystal Spire shattered. The blue liquid in the lake boiled upward, turning into a blinding pillar of light.
The shockwave hit everyone.
Vesper was thrown into a wall. Stroud was knocked off his perch. Silas was buried under falling debris.
Jax was lifted off his feet and sucked into the vortex of light.
"Jax!" Isobel screamed, reaching out with a shadow-tendril, but the light burned it away.
Jax tumbled through the air, weightless. He wasn't falling down. He was falling in. The energy of the Heart wrapped around him, filling his ears, his lungs, his veins.
It didn't feel like the battery acid of the train. It didn't feel like the dirty electricity of the rat-cable.
It felt like a song.
And then, Jackson Miller disappeared into the light.
The Aftermath
The light faded. The cavern was silent.
The lake was gone. The crystal spire was gone. In its place was a crater of smoking, blackened glass.
Silas shoved a pile of rubble off his chest. He coughed, his suit whining in protest.
"Isobel?" he croaked.
Isobel pulled herself up from behind a ridge. She looked at the crater. She looked at the empty space where Jax had been.
"He's gone," she whispered.
On the other side of the crater, Kaelen stood up. His armor was fused, his weapons dead. Vesper limped to his side, clutching a broken arm. Stroud was nowhere to be seen, likely buried in the collapse.
Kaelen looked at Silas and Isobel. He looked at the destroyed Nexus.
"Target neutralized," Kaelen said, his voice distorted by his damaged helmet. "The Heart is destroyed. The city will fall within the week."
He didn't attack. He simply turned around.
"We are done here. Moving to extraction."
The Greyhawks began the long climb back to the surface.
Silas tried to stand, but his leg finally gave out. He fell back against the stone.
"We failed," Silas said, staring at the ceiling. "We led them right to it."
Isobel walked to the edge of the crater. She looked down into the smoking glass.
She closed her eyes. She listened.
"No," Isobel whispered.
She turned to Silas, a strange, terrifying hope in her eyes.
"Silas... the heartbeat didn't stop."
She pointed at the crater.
"It just moved."
Deep in the glass, a faint, rhythmic blue light began to pulse. Not from the earth. But from something buried under the glass.
Thump-thump.
Thump-thump.
The Chicago Heart hadn't been destroyed. It had found a host.