The first sapper didn't scream. He just died.
Narcissus met the charge with a shoulder check that cracked the man's sternum. The sapper flew backward, tripping the two men behind him.
"Hold the line!" Narcissus roared.
He swung his torch like a club. Burning pitch sprayed across the darkness. It struck a sapper in the face, igniting his leather mask. The man thrashed, illuminating the tunnel in chaotic flashes of orange light.
Marcus stepped into the gap.
A pickaxe swung at his head.
Duck. The Ghost's instinct fired before Marcus's brain could process the threat.
He dropped. The steel tip whistled inches above his ear.
Marcus thrust upward. His gladius punched through the sapper's groin, angling into the gut. It was a dirty, ugly kill.
He ripped the blade free. Hot blood soaked his hand.
"Push them back!" Varus shouted.
The traitor general was fighting like a demon. He had no shield, only a sword scavenged from a corpse. He parried a shovel strike and slashed the attacker's throat in one fluid motion.
But there were too many of them.
The tunnel was narrow, but the enemy sappers were relentless. They weren't fighting for territory. They were fighting to delay.
"They're falling back!" Crixus yelled.
The enemy line suddenly broke. The sappers turned and sprinted deeper into the darkness, extinguishing their torches as they ran.
"Don't chase!" Marcus commanded.
Silence crashed back into the tunnel. The only sounds were the ragged breathing of the survivors and the dripping of water.
"It's a trap," Narcissus growled, wiping blood from his eyes. "They want us to follow."
Marcus nodded. He knelt, fumbling with the straps of the rugged leather case Crixus had protected during the fall.
He opened the laptop. The screen glowed blue, cutting through the gloom.
"Galen," Marcus whispered. "Keep the light covered. Don't let them see us."
Galen huddled over him, shielding the screen with his dirty tunic. The physician was shaking, his eyes wide with shock.
"What are you doing?" Galen hissed. "We need weapons, not philosophy!"
"This is a weapon," Marcus muttered.
He tapped a key.
SYSTEM: ACOUSTIC MAPPING INITIATED.
INPUT: MICROPHONE ARRAY.
MODE: ACTIVE SONAR.
"Quiet," Marcus ordered. "Everyone."
He picked up a loose stone and hurled it down the pitch-black tunnel.
Clack. Clack. Clack.
The echoes bounced off the stone walls, returning to the laptop's microphone.
On the screen, a wireframe map constructed itself in real-time. Blue lines sketched the contours of the dark.
The tunnel went straight for thirty yards. Then it widened into a chamber.
And in that chamber, five heat signatures were motionless. Waiting.
ANOMALY DETECTED. JARVIS highlighted a section of the ceiling in the forward chamber. UNSTABLE STRATA. EXPOSED TIMBER.
"They aren't fighting us," Marcus realized, staring at the screen. "They're waiting to pull the supports. They want to bury us."
He looked at Varus. "Thirty yards. Then a trap. They'll drop the ceiling the moment we step inside."
Varus gripped his sword. "Then we run fast?"
"No," Marcus said. "We trigger it early."
He looked at Crixus. "The pilum. Give it to me."
Crixus handed over a heavy throwing spear he had retrieved from a dead Praetorian.
Marcus handed it to Narcissus. "You have the best arm. Aim for the ceiling. High arc."
Narcissus weighed the spear. He couldn't see the target. He had to trust the ghost in the machine.
"Guide me," the gladiator said.
Marcus watched the screen. "Five steps forward. Angle forty-five degrees."
Narcissus stepped into the darkness. He cocked his arm back, the muscles of his shoulder bunching like coiled rope.
"Now!" Marcus whispered.
Narcissus grunted, hurling the spear with explosive force.
The weapon vanished into the black.
A second passed. Two.
THWACK.
The sound of wood splintering echoed back.
Then, a rumble.
The tunnel ahead shook violently. A cloud of dust billowed out toward them as the trap collapsed prematurely. The screams of the enemy sappers were cut short as tons of rock crushed the ambush team.
"Move!" Marcus shouted. "Before the dust settles!"
They sprinted into the cloud.
They scrambled over the pile of fresh rubble. Beneath the stones, limbs twitched. They didn't stop to finish them off.
They emerged into a wider ventilation shaft. The air here was moving, pulling upward.
"Wait," Varus said, holding up a hand.
He pointed ahead.
A single enemy soldier was crouching by a wooden crate, trying to strike a flint. He was terrified, his hands shaking so hard he kept missing the spark.
Beside him sat a clay pot with a burning fuse. A primitive blasting charge.
He wasn't trying to collapse the roof. He was trying to seal the exit.
"He's blowing the shaft!" Crixus yelled.
The soldier looked up, panic in his eyes. He finally struck the spark. The fuse hissed to life.
It was too far. They couldn't reach him in time.
Varus didn't hesitate.
The traitor general dropped his sword and sprinted.
"For Rome!" Varus screamed.
An arrow flew from the shadows beyond the bomber—a second guard covering the demolition.
The shaft struck Varus in the shoulder, spinning him around.
He didn't fall. He used the momentum to throw himself forward.
He collided with the bomber, tackling him away from the explosive. They hit the wall with a sickening crunch.
The fuse was burning down. Sparks spat onto the clay rim.
Varus scrambled up, ignoring the arrow protruding from his deltoid. He grabbed the clay pot.
He didn't try to extinguish it. There was no time.
He hurled it down a side fissure—a drainage pipe cut into the rock floor.
BOOM.
The explosion happened deep in the pipe. The ground jumped beneath their feet. A geyser of smoke and fire shot out of the drain, singing Varus's eyebrows, but the main tunnel held.
Varus collapsed against the wall, clutching his shoulder. Blood leaked through his fingers.
Marcus reached him first. He grabbed Varus by the tunic, checking the wound. It was deep, but it hadn't hit the lung.
"You idiot," Marcus breathed.
Varus grinned through gritted teeth. "Debt... paid."
Marcus looked at the general. The distrust in his gut uncoiled, just a little.
"Debt paid," Marcus agreed. "Narcissus, get him up."
They reached the end of the shaft. It opened into a large vertical chimney, leading up to the surface. Wooden rungs were hammered into the rock.
But something else was here.
Stacked against the wall were copper tanks. The same tanks the Alchemists had worn.
Galen limped over to the chimney. He held a wet hand up to the rushing air.
"The draft," Galen rasped, his eyes lighting up with a manic scientific curiosity. "It pulls from the valley floor and vents out near the enemy camp. It's a ventilation system for the mines."
Marcus looked at the copper tanks. Then he looked at the chimney.
A vicious idea formed in his mind.
"They tried to smoke us out," Marcus said. "Let's return the favor."
"Crixus," Marcus commanded. "Puncture the tanks."
The gladiator swung his axe. Clang. Clang.
Green liquid gushed from the copper vessels, pooling on the stone floor near the chimney intake. The smell of sulfur and oil filled the small chamber.
"Fire," Marcus said.
Narcissus lowered his torch.
The liquid caught instantly. It didn't just burn; it roared. The chemical reaction was violent and immediate.
Because of the draft, the flames didn't come back toward them. The chimney sucked the fire and the thick, toxic green smoke upward, accelerating it like a cannon blast.
THERMAL DRAFT CONFIRMED. JARVIS calculated. TOXIC PLUME EXITING AT COORDINATES 44.2—DIRECTLY INTO ENEMY FORWARD COMMAND.
Somewhere above them, on the ridge occupied by Valerius's army, all hell was breaking loose.
"Climb," Marcus ordered. "While they're choking."
They scrambled up the service ladder, lungs burning.
Ten minutes later, they emerged.
They pushed open a grate hidden in a rocky outcrop. They weren't in the enemy camp. They were back inside the ruins of their own hill fort, near the rear wall.
The sun was rising. The light was blinding after the dark of the tunnels.
Marcus pulled himself out of the hole and collapsed on the dirt. Narcissus dragged Varus out after him.
The scene inside the fort was a nightmare.
The central courtyard was a crater. The dust was still settling. Thousands of men were gone—swallowed by the collapse.
But the enemy attack had stopped.
Across the valley, green smoke billowed from the ground in the middle of Valerius's camp. Tents were burning. The enemy lay in disarray, coughing and retreating from the toxic cloud.
They had won. They had survived the fire, the fall, and the dark.
Marcus sat up, wiping sweat and grime from his face. He looked around at his decimated army.
The survivors were huddled against the walls. They looked broken.
"Water," a soldier croaked nearby. "Please."
Marcus froze.
He looked at the crater in the center of the fort.
The collapse hadn't just taken the command tent. It had taken the ground beneath the main plaza.
Where the cisterns were.
SCANNING... JARVIS's text was cold and merciless.
STRUCTURAL DAMAGE REPORT:
MAIN CISTERN: RUPTURED.
SECONDARY CISTERN: COLLAPSED.
CURRENT WATER RESERVES: 0 LITERS.
Marcus stood up, walking to the edge of the sinkhole. He peered down.
Deep in the rubble, he saw wet mud. The water—weeks of supply—had drained away into the deep earth, wasted in the collapse.
They had forty thousand men. And not a drop to drink.
The sun beat down on Marcus's neck. It was going to be a hot day.
"Caesar?" Narcissus asked, stepping up beside him. "What are your orders? We need to ration the water."
Marcus looked at his loyal dog. He looked at Varus, bleeding for a cause he just joined. He looked at the thousands of thirsty men waiting for him to save them.
He let out a dry, ragged laugh.
"There is no water to ration, Narcissus."
He pointed at the sun.
"The enemy didn't need to kill us," Marcus whispered. "They just had to wait for noon."
SURVIVAL ESTIMATE WITHOUT HYDRATION: 36 HOURS.
The siege wasn't over. The dying had just begun.