The final three proved even easier to deal with.
Although the team had exhausted its explosives, they had slipped into the nearby hazardous materials storage room and helped themselves to plenty of supplies.
Jonathan fashioned several makeshift charges, powerful enough to injure the Predators without bringing down the corridor.
When the Predators saw a round object flying toward them from a distance, one even lowered its head and curiously prodded it with a claw.
"BOOM——!!!"
The charge detonated violently. Flames erupted from the corridor entrance, thick smoke billowed outward, and fragments rained from the ceiling.
"Get down!"
The group, secretly hiding around the corner, threw themselves to the floor and covered their heads.
The shockwave swept overhead, carrying searing heat and debris with it.
More than ten seconds later, the shaking gradually subsided.
Calista raised her head, coughing as she waved away the smoke and dust. "Jonathan... are you sure you only used 'a little' high-energy gel?"
"I... I'm sure..." Jonathan looked just as confused. "Unless those containers had something else mixed in..."
"Forget it. Check the door!"
They rushed back to the corridor entrance.
The airlock door had been blown completely off, its metal panel embedded in the opposite wall.
The frame was badly warped, but the blast had opened a gap wide enough for two people to pass through side by side.
But what had happened to the three Predators guarding it?
As the smoke cleared, they saw the answer.
One had been sliced cleanly in half by the flying metal door panel and lay beside the entrance.
Another had been hurled halfway down the corridor by the shockwave. Its body was fractured in several places, and although it was still struggling, it had lost the ability to fight.
The strongest one, which had prodded the explosive, had its entire brain growth blown apart like a rotten watermelon. It was thoroughly dead.
With their greatest obstacle removed and only a handful of Claw mutants left inside the plant, they finally reached the place where the leak had begun.
The core area of the D-7 Laboratory was roughly thirty meters in diameter, with a floor made of smooth synthetic material. A massive cylindrical bioreactor stood in the center of the chamber.
The tank was made from transparent reinforced glass, but it now stood completely empty. Only a few dried, dark stains and several broken pipes remained at the bottom.
There were no walkers and no Black Fire mutants.
Bossie had been eager to get started for some time.
He rushed to the nearest terminal, pulled his portable device from his backpack, and connected it to the data port.
"The system has an independent power supply and is still running. I just need to break through the final firewall..."
Calista gave a hand signal, and the others immediately formed a defensive perimeter.
After making a circuit of the laboratory, she stopped behind Bossie and watched the scrolling code and progress bar on the screen.
"How much longer?"
"Almost there. I'm in!"
A simple interface appeared on the main screen.
A file directory filled the left side, while the center displayed log previews.
Bossie scanned it briefly, then immediately began downloading every file related to Black Fire.
Calista silently read through the file names beside him until one crucial document caught her attention:
Factory Emergency Report
Its contents were chilling and extremely brief, as though they had been recorded in a desperate hurry.
When the walker outbreak spread across the world, the Singularity Polymers Plant had been at a critical stage of the "Biological Unit Induction Experiment."
The military squad stationed there received orders to recover all experimental data, samples, and the nerve agent developed at the facility. They were then to decontaminate the experimental area and evacuate before conditions outside deteriorated further.
"Nerve agent..." Calista murmured.
Bossie scrolled through the report. "Yes. According to this, the military squad had prepared a crate of nerve agent for evacuation. But..."
He paused and took a deep breath.
"There was a total power failure. The backup system could only keep the core area operational, and containment throughout the experimental zone failed.
"The researchers and walkers trapped inside had already begun mutating. They broke out, caught the military squad by surprise, and killed or wounded more than half of them in the fighting."
"What happened to the nerve agent?" Calista pressed. "The crate they were supposed to evacuate?"
Bossie pointed toward the final lines of the report.
"Because the evacuation was rushed and a large-scale walker outbreak had also erupted throughout the industrial park, they couldn't take the crate with them.
"It was temporarily stored in the Block A Raw Material Warehouse for later recovery and disposal. A military officer who failed to evacuate recorded this during an emergency transmission to his teammates."
Block A Raw Material Warehouse.
Calista's pupils contracted sharply.
The crate taken by the Throat-Slasher Gang, the one that had poisoned more than half their people, had contained the nerve agent.
Fortunately, it had been released outdoors and in a relatively small dose, so it had not caused any horrific mutations. Or perhaps those unlucky victims had been killed by their companions immediately after turning, before they had time to mutate.
It could only be called fate.
Bossie's fingers flew across the keyboard one final time. Then he collapsed against the back of his chair and released a long breath.
"Calista, we have the data. Every record, from the Oak Ridge Memorandum of Understanding to the final accident report from the Singularity Polymers Plant. It's all here."
Calista turned to the others. "Rest for half an hour. Then we're leaving."
Half an hour later, they retraced their route.
They encountered only three Claw mutants along the way. Eager to return home, the group swarmed them and quickly finished them off.
At that moment, a violent burst of static erupted through their headsets. Then a broken human voice came through.
"...Calling... task force... rescue team... unit... respond if you can hear... this is... Command Center... repeat... respond if you can hear..."
The signal was extremely unstable, but it sounded like music to their ears.
"It's Command Center!" Bossie's voice rose with excitement as he frantically adjusted the antenna and frequency. "Damn it, we finally have a signal!"
A noisy response came over the radio.
"...Copy... hold on... extraction team dispatched... expected arrival at your entry point... hold on..."
Despite being close to physical collapse, everyone unconsciously quickened their pace for the remainder of the journey.
When they finally emerged through the opening cut into Raw Material Loading Dock No. 3, they felt as though they had returned from another world.
The daylight was dim.
It was not dawn, but dusk.
Lead-gray clouds hung low, obscuring the setting sun. Only faint embers of dark red and orange remained along the horizon.
They had fought and struggled deep within the dark factory, unaware that nearly two full days had passed.
"The oxygen tanks..." Jonathan glanced at the gauge on the tank strapped to his back. Its needle was almost at zero. "They lasted... exactly forty-eight hours..."
Coincidence or luck?
No one gave it much thought.
The Defense Force extraction team had already been waiting anxiously for some time. The moment they saw the group emerge, they rushed forward to meet them.
A familiar figure jumped from one of the vehicles and hurried toward them.
Rickson had personally come to receive them.
God only knew how he had endured the past two days with both of the base's top leaders completely out of contact.
Calista removed the mask she had worn for so long and quickly reported, "The cleanup is complete. The contamination inside is continuing to dissipate. There may still be a few mutated walkers, but they don't pose much of a threat.
"Frank and Anderson... didn't make it out."
She paused.
"Their bodies are still inside, near the D-7 Core Laboratory and the areas where we fought earlier. We marked the locations with fluorescent paint."
Rickson nodded solemnly, then turned and gave instructions to one of the soldiers. The man immediately returned to the vehicle and began contacting the base through its radio.
"We'll send people inside to recover them," Rickson said heavily. "For now, get in the vehicle."
Calista was the last to board.
She stood beside the vehicle and looked back at the pitch-black entrance.
The Singularity Polymers Plant stood silent in the twilight. Its depths held buried secrets and buried dead.
"Calista?" Rickson called from the vehicle.
She tore her gaze away and climbed aboard.
"Let's go. We're going home. There's still a lot to do, and a lot of people... we need to remember."