**Chapter 4: Undercurrents**

Yan Xiu stood outside the burned-out evidence room of the police station, staring at the smoke-stained walls. Firefighters were putting out the last of the flames, and the air was thick with the acrid smell of charred debris. His fingers unconsciously rubbed the USB drive in his pocket as his mind replayed the string of code he had seen earlier.

"Are you sure you want to do this?" Lin Xia's voice came from behind him.

Yan Xiu turned to see the concern etched on her face. Her police uniform was smudged with soot, and strands of hair clung to her forehead, making her look disheveled.

"It's the only lead we have," he said softly. "And I can't shake the feeling that this USB drive holds the truth about my father."

Lin Xia sighed. "But the evidence room is destroyed, and the quantum computer is gone. How are we going to crack this USB drive?"

Yan Xiu's gaze shifted past her to where Zhang Hao was being questioned. The real Zhang Hao had been found unconscious in the police station's underground parking lot before the fire and still looked weak.

"I remember," Yan Xiu said thoughtfully, "Captain Zhang once mentioned an underground hacker group. They might have the equipment we need."

Lin Xia frowned. "You mean the 'Dark Web'? But that's too dangerous. We don't even know if we can trust them."

"Exactly because it's dangerous," Yan Xiu said, "it's more likely to lead us to the truth."

At that moment, Zhang Hao approached. His face was still pale, but his eyes had regained their usual sharpness.

"I heard about what you found in the evidence room," he said. "About that USB drive..."

Yan Xiu cut him off. "Captain Zhang, I need you to introduce me to someone from the 'Dark Web.'"

Zhang Hao's expression froze. He glanced around cautiously and lowered his voice. "How do you know about that..."

"You left a clue in the parking lot before you were knocked out," Yan Xiu said. "A note with 'Dark Web' written on it."

Lin Xia looked at them in surprise. "Wait, Captain Zhang, you've been investigating the 'Dark Web'?"

Zhang Hao gave a bitter smile. "It's a classified mission. But it seems the secret's out now." He turned to Yan Xiu. "Are you sure about this? The people in the 'Dark Web' aren't easy to deal with."

Yan Xiu nodded. "For the truth, I'm willing to take the risk."

As night fell, the three of them drove to a derelict industrial area on the outskirts of the city. The abandoned factories cast eerie shadows under the moonlight, and the distant howls of stray dogs echoed through the air.

"This is it," Zhang Hao said, stopping the car. "Remember, once we're inside, don't make any sudden moves. The 'Dark Web' people hate being tested."

They entered a seemingly abandoned factory, but inside was a completely different world. Modern equipment glowed faintly under dim lights, and a dozen masked individuals were busy operating various machines.

"Officer Zhang," a hoarse voice came from the shadows. "Bringing guests?"

A tall, thin man stepped out, wearing a silver mask that revealed only his sharp eyes.

"This is Yan Xiu," Zhang Hao introduced. "He needs your help."

The masked man studied Yan Xiu. "I've heard of you. The programmer who cracked the 'Raven Paradox.'"

Yan Xiu was surprised. "How do you know that?"

The masked man chuckled. "In the 'Dark Web,' nothing is truly a secret. But..." His gaze fell on the USB drive in Yan Xiu's hand. "What you've brought here is quite interesting."

Yan Xiu handed over the USB drive. "I need to decrypt its contents."

The masked man took the drive and examined it closely. "Quantum encryption, and the latest model at that. Interesting." He turned to a massive machine. "But before we begin, you'll need to pass a little test."

The machine booted up, and a complex logic puzzle appeared on the screen.

"This is..." Lin Xia said in surprise.

"A simple entry test," the masked man said. "If you can't solve this, there's no point in continuing."

Yan Xiu stared at the screen, his mind racing. The puzzle appeared intricate, but it was actually a variation of the "Prisoner's Dilemma." He quickly entered a string of code, and the screen flickered, displaying the word "Pass."

The masked man nodded approvingly. "Not bad. It seems you're qualified to play this game."

He inserted the USB drive, and the machine whirred to life. Suddenly, the lights in the room flickered, and the machine emitted a piercing alarm.

"Damn it!" the masked man cursed. "This USB drive has a self-destruct program!"

Yan Xiu immediately stepped forward. "Let me handle it!"

His fingers flew across the keyboard as he tried to stop the program. But he soon realized the self-destruct mechanism was far more complex than he had anticipated.

"Need some help?" a clear female voice came from behind.

Yan Xiu turned to see a girl wearing a cat-eared mask. Her eyes were an unusual shade of purple, glowing mysteriously in the dim light.

"Who are you...?"

"Call me 'Night Cat,'" the girl said. "I have some experience with quantum encryption."

She squeezed next to Yan Xiu and quickly entered a string of complex code. The machine's alarm gradually subsided, and the data on the screen began to display normally.

"How did you do that?" Yan Xiu asked in amazement.

Night Cat smiled mysteriously. "Everyone has their secrets, don't they?"

At that moment, the contents of the USB drive finally appeared. It was a detailed list of dozens of names and their corresponding positions, including prominent figures in politics and business.

"This is..." Lin Xia gasped.

"A vast underground network," Yan Xiu said. "And my father's name is on it."

His trembling finger pointed to the end of the list. There, it clearly read: "Yan Mingyuan, Lead Programmer, Deceased."

The masked man spoke up. "It seems you've stumbled into a conspiracy far bigger than you imagined."

Night Cat leaned closer to the screen, studying the list. "These names... I feel like I've seen them somewhere before."

Just then, police sirens blared outside. Zhang Hao's face turned pale. "We need to leave. Now!"

The masked man quickly shut down the machine. "You need to get out of here. We'll handle this."

Night Cat shoved a USB drive into Yan Xiu's hand. "This has my contact information. If you need help, call me anytime."

The three of them hurried out of the factory. As they reached their car, several police cars sped past.

"Get in!" Zhang Hao shouted.

They had just started the car when gunfire erupted behind them. Lin Xia looked back and saw masked figures exchanging fire with the police.

"What's going on?" she exclaimed.

Yan Xiu gripped the USB drive tightly, his expression grim. "It seems someone doesn't want us to know the truth."

As the car sped through the night, Yan Xiu stared out at the passing cityscape, a sense of foreboding growing in his chest. He couldn't shake the feeling that this night was only the beginning, and a much larger storm was brewing.

The car raced through the empty streets, the city lights blurring into streaks of color. Yan Xiu sat in the backseat, his mind racing as he processed everything that had just happened. The USB drive in his hand felt like a ticking time bomb, its contents both a key to the truth and a potential catalyst for disaster.

Lin Xia glanced at him from the passenger seat. "What do we do now? If the police are involved, we can't trust anyone."

Yan Xiu's eyes remained fixed on the USB drive. "We need to analyze this list. If my father's name is on it, there must be a connection to his death. And if these people are willing to kill to keep it secret..."

Zhang Hao, gripping the steering wheel tightly, interrupted. "We need to lay low for now. If they're willing to attack a police station, they won't hesitate to come after us."

Yan Xiu nodded. "Agreed. But we can't stop now. This list—it's not just names. It's a map of their entire operation. If we can decode it, we might be able to stop them before they strike again."

Lin Xia turned to face him. "But how? We don't have the resources, and we can't trust anyone in the system."

Yan Xiu's gaze shifted to the USB drive Night Cat had given him. "We have one ally. Someone who knows the 'Dark Web' better than anyone."

Zhang Hao frowned. "You mean that girl? Yan Xiu, we don't even know who she is. For all we know, she could be working for them."

Yan Xiu shook his head. "No. If she wanted to stop us, she could have let the self-destruct program run. She helped us. That means she has her own reasons for wanting to expose this."

Lin Xia sighed. "Even if we trust her, how do we contact her? We can't just waltz back into that factory."

Yan Xiu held up the USB drive. "She gave me this for a reason. There's a way to reach her—we just need to figure it out."

The car pulled into a secluded parking garage beneath an apartment building. Zhang Hao led them to a safe house, a small but well-equipped space with multiple computers and surveillance equipment.

"One of our backup locations," Zhang Hao explained. "It's off the books, so it should be safe for now."

Yan Xiu immediately set up one of the computers and inserted Night Cat's USB drive. The screen lit up with a series of cryptic symbols and coordinates.

Lin Xia leaned over his shoulder. "What is this? Some kind of code?"

Yan Xiu's fingers flew across the keyboard. "It's a cipher. She's left us a way to contact her, but we need to solve this first."

As Yan Xiu worked, Lin Xia and Zhang Hao kept watch, monitoring the security feeds for any signs of trouble. Hours passed, and the tension in the room grew palpable.

Finally, Yan Xiu let out a breath. "Got it."

The screen displayed a message: "If you're reading this, you're ready. Meet me at the coordinates below. Come alone."

Lin Xia frowned. "Alone? That's too risky."

Yan Xiu stood up. "It's the only way. If we want her help, we have to play by her rules."

Zhang Hao crossed his arms. "I don't like this. But if you're set on going, at least let us set up a perimeter. We'll be nearby in case things go south."

Yan Xiu nodded. "Agreed."

The coordinates led to an abandoned subway station on the outskirts of the city. The platform was dimly lit, the air thick with the smell of damp concrete and rust. Yan Xiu stood alone, his senses on high alert.

A soft sound echoed through the station, and Night Cat emerged from the shadows. She was no longer wearing the cat-eared mask, but her purple eyes still gleamed with an otherworldly intensity.

"You came," she said, her voice carrying a hint of amusement.

Yan Xiu held up the USB drive. "You knew I would. Now tell me, what's your stake in all this?"

Night Cat stepped closer. "Let's just say I have my own reasons for wanting to bring them down. But I can't do it alone. That's where you come in."

Yan Xiu studied her. "Why should I trust you?"

She smiled faintly. "You don't have to trust me. You just have to trust that our goals align—for now."

Yan Xiu nodded slowly. "Fair enough. What do you know about the list?"

Night Cat's expression turned serious. "It's more than just a list. It's a blueprint. These people—they're not just corrupt officials or businessmen. They're part of a larger network, one that's been manipulating the city for years. Your father was one of the few who tried to stop them."

Yan Xiu's heart clenched. "What happened to him?"

Night Cat's gaze softened. "He got too close. They couldn't risk him exposing their operation, so they made it look like a suicide. But he left clues—like that USB drive. He knew someone would come looking for the truth."

Yan Xiu's fists clenched. "And now they're after me."

Night Cat nodded. "You're the key to unraveling everything. But you're also their biggest threat. That's why they're getting desperate."

Yan Xiu took a deep breath. "Then let's not waste any more time. What's the next move?"

Night Cat's lips curved into a sly smile. "We hit them where it hurts. Their data hub. If we can infiltrate it, we can expose their entire operation."

Yan Xiu's eyes narrowed. "Where is it?"

Night Cat's smile widened. "Right under their noses. The city's central data center. But getting in won't be easy. They've got layers of security, both digital and physical."

Yan Xiu's mind raced. "We'll need a plan. And backup."

Night Cat shook her head. "No backup. Too risky. It has to be just us."

Yan Xiu hesitated, then nodded. "Alright. Let's do this."

As they left the subway station, Yan Xiu couldn't shake the feeling that they were walking into a trap. But he also knew there was no turning back. The truth was within reach, and he was willing to risk everything to uncover it.

The city's central data center loomed ahead, a towering structure of glass and steel. Inside, the answers to his father's death—and the fate of the city—awaited.

Yan Xiu took a deep breath and stepped into the shadows, ready to face whatever lay ahead. The game was far from over, and the stakes had never been higher.