The sun had nearly slipped completely beneath the western horizon, leaving a dark purple streak hugging the buildings of Rajawali High. The school was quiet. Normal students had gone home, enjoying warm dinners or preparing for expensive tutoring sessions. The school security guards had begun their routine patrol, locking the side gates.
However, on the 3rd Floor, inside the laboratory nicknamed "Rehan's Cave," digital life was just beginning.
Rehan was still sitting in the same position as he was hours ago. His hollow eyes reflected the blue light from rows of code scrolling on the screen. He had just finished Alya's "order"—altering items in the digital purchase request. Physically, the delivery order to the pharmacy warehouse requested Antibiotics and IV Drips worth 50 million. But digitally, the invoice sent to the School Treasurer read as "Premium Hand Sanitizers & N95 Masks" with the exact same total price.
Official school money went out, contraband goods came in. No cost discrepancy, no suspicious audit. A neat, clean, and traceless piece of digital art.
He stretched his body, hearing a satisfying crack from his spine. He thought today was over. He thought he could go back to enjoying his holy solitude.
But, the motion sensor in the corridor outside the lab—which he had installed illegally and connected to his third monitor—blinked red.
Someone was there.
Rehan clicked his tongue. "Who is it now? Did Dani leave his PS controller?"
Rehan shifted his gaze to the corridor CCTV feed. On the grainy black-and-white screen, he saw a skinny male figure, wearing a jacket slightly too big for him and a backpack that looked heavy. The figure didn't bang on the door brutally like Dani. Nor did he look around in panic like a lost student.
The figure just stood in front of the lab's glass door, staring straight at the CCTV camera hidden in the ceiling corner.
It was Salim.
And what made the hair on Rehan's neck stand up slightly was this: Salim was smiling at the camera. He knew Rehan was watching. Salim then held up a piece of paper in front of the lens. On that paper was written a string of binary numbers:
01001000 01000101 01001100 01010000
Rehan frowned, translating the binary in his head in split seconds.
H-E-L-P.
"Dramatic," Rehan muttered. But his curiosity was piqued. Salim wasn't the type to ask for help without a strong reason. And the fact that he used binary—Rehan's mother tongue—was a tribute, or perhaps an intelligence bait.
Click.
Rehan pressed the magnetic door release button.
Salim stepped inside. A blast of cold air from the server AC immediately welcomed him. He looked around the room filled with LAN cables, stacks of used hard drives, and cyberpunk posters plastered on the walls.
"Cozy den you got here, Han," Salim commented casually, as if visiting a cafe, not the school hacker's lair. "Temperature's perfect for preserving a corpse. Or a server. Same thing, really."
"You have three minutes before I kick you out," Rehan said bluntly, spinning his chair to face Salim. He didn't offer Salim a seat. "And I hope you're not here to ask for a Math grade cheat. Because I know you don't need that."
Salim chuckled, placed his bag on the floor, then sat on top of a used CPU casing lying in the corner—completely ignoring guest etiquette.
"Grades are temporary, Han. I'm here for something more... eternal," Salim said. He reached into his pocket, pulling out a magnetic library card. The card was worn, its edges peeling.
"Library card?" Rehan raised an eyebrow. "You want me to wipe your late fees? That's petty, Lim."
"No," Salim shook his head. His eyes looked at Rehan with a different intensity. The gaze of an architect looking at a building foundation. "I want you to help me create a 'Ghost'."
"A Ghost?"
"I've been observing the RFID (Radio Frequency Identification) system in our library," Salim explained, his voice turning serious. "Every book has a chip. Every time that book passes the sensor gate without being scanned at Mrs. Rini's desk, the alarm sounds. The system is simple: If Tag Detected AND Status Not Checked-Out, THEN Alarm ON."
"Standard," Rehan cut in, bored. "Even a middle schooler understands that logic."
"Correct. But I found a loophole in the algorithm," Salim continued. He picked up a whiteboard marker lying on Rehan's desk, then wrote a simple probability formula on the room's glass partition.
"The system has a read delay of 0.5 seconds for database verification. If two signals enter simultaneously with slightly shifted frequencies—one real signal, one ghost signal—the system gets confused. It reads the book as leaving, but the status in the database remains 'Available'."
Salim looked at Rehan. "I've calculated the frequency mathematically. But I need you to execute the code. I need you to make a small program that can 'duplicate' this card's signal in the system, as if someone else is borrowing the book at the exact same time I pass the gate."
Rehan fell silent. He looked at the formula Salim wrote on the glass. It wasn't computer code. It was pure mathematics. Wave calculation. But if translated into machine language... it made sense.
"What for?" Rehan asked, eyes narrowing in suspicion. "What book do you want to steal? Encyclopedia Britannica? Or are you just bored?"
Salim leaned his back against the wall. His face returned to being flat, hiding his true motives.
"Consider it a scientific experiment," Salim answered. "I'm just curious, Han. In this increasingly digital world, just how easy is it to manipulate reality? If the System says the book is on the shelf, but it's actually in my bag... which one is the truth? Physical reality, or data reality?"
Rehan stared at Salim intently. He saw something familiar in Salim's eyes. Loneliness. Not social loneliness like having no friends, but intellectual loneliness. The loneliness of seeing patterns others didn't see.
Rehan spun his chair back to face the screen. His fingers began to dance on the keyboard.
"You need signal spoofing," Rehan muttered, entering work mode. "I can write a simple Python script to inject a fake signal into the library server. But I need your card's unique ID."
"1209-SALIM-SCI1," Salim stated quickly.
"Okay. And the target book?"
"Any book. That Stoicism philosophy book works."
Silence filled the room again, broken only by the rapid rhythm of Rehan's typing. Salim watched Rehan work. He didn't understand the code syntax, but he understood the logic flow. Rehan was building a bridge between Salim's mathematical theory and digital practice.
"You know, Han," Salim said suddenly amidst the silence. "Dani was right about one thing."
"What?" Rehan asked without stopping typing.
"You need a friend. Not for gaming or partying. But because a brain like yours is dangerous if left alone," Salim said. "You need a counterbalance. Someone to give you purpose, so your skills aren't just used for hacking toilet CCTVs or pranking teachers."
Rehan paused typing for a moment. That sentence struck a chord.
"And you think you are the counterbalance?" Rehan asked cynically.
"Maybe. I have plans, Han. I have many plans in my head," Salim pointed to his temple. "But my plans are just abstract concepts without an executor like you. We are... an odd collaboration. I'm the software, you're the hardware. Or vice versa."
"Don't compare me to hardware. I'm the Kernel," Rehan corrected arrogantly, but the corner of his lip lifted slightly.
"Done," Rehan said five minutes later. He plugged a small flash drive into his computer, transferring the program.
Rehan tossed the flash drive to Salim. Salim caught it with reflexes that were surprisingly good for someone who rarely exercised.
"Plug that into the USB port behind Mrs. Rini's desk when she's not looking. The program will autorun. Every time your card is scanned, it sends a double signal. The system will think it's a glitch and let you pass without an alarm, while the book status in the database remains safe," Rehan explained.
Salim gripped the flash drive. It felt cold in his palm.
"Thanks, Han," Salim said. "You're not asking for payment?"
"Consider it an investment," Rehan replied, spinning his chair away from Salim again. "I want to see how far this 'reality experiment' of yours can go. But remember, Lim. If you get caught, I don't know you. And that flash drive will auto-format in 24 hours."
"Fair," Salim stood up, slinging his bag.
When Salim reached the door, he stopped for a moment.
"Han," Salim called.
"What now?"
"The Study Tour... bring your laptop. I have a hunch we're going to need more than just a library script," Salim said. His tone changed, heavier, darker. As if he was talking about war, not a vacation.
Rehan went silent. Salim's hunch aligned with Alya's message yesterday. The lives of the entire cohort are at stake. Why were the smart people around him suddenly becoming paranoid? Or maybe, they were actually the sane ones?
"I always bring my laptop. It's my life," Rehan answered.
Salim nodded, then walked out of the room. The magnetic door closed, locking Rehan back in his silence.
Rehan stared at his now-blank monitor screen. He reopened the CCTV window. He watched Salim walking away down the empty corridor.
"An odd collaboration, huh?" Rehan muttered.
He opened his desk drawer, taking out his assembled Signal Jammer device. He weighed it in his hand. Earlier, he only planned to bring it to prank Dani by killing his phone signal if he got too loud on the bus. But after Salim's visit, Rehan felt he had to upgrade the device's range.
Rehan turned back to his computer. He started typing new lines of code. Not for the library, not for Alya. But for himself. An offline-based GPS signal mapping program.
"If physical reality and data reality collide..." Rehan whispered, repeating Salim's words, "...I want to make sure I'm the one holding the remote control."
Outside, night had fully descended upon Rajawali High. The night wind blew hard, shaking the old banyan trees in the schoolyard. The rustling leaves sounded like whispered warnings.
Unbeknownst to them, the wheels of fate had turned. Salim with his logic, Alya with her intuition, and Rehan with his code, were unconsciously preparing their weapon loadouts. They were building a firewall before the real virus attacked.
And that "virus" was currently sitting comfortably in the Principal's office, smiling kindly while holding the approved Study Tour proposal. That virus wasn't computer code, but a malicious plan wrapped in a gold ribbon labeled "Character Education."
Rehan didn't know that the small script he gave Salim—the "Ghost" concept or the double signal—would someday become the only way for Salim to trick the tracking tablets on the Island of Death. That the little experiment in the library was a dress rehearsal to save their lives from the bombs planted in the old building.
This odd collaboration had just laid its first stone.