Chloe's curiosity spiked rapidly. She grabbed the phone, her eyes scanning the blocks of text until she hit the bottom of the page.
"The last sentence is 'Shadows crept across the floor,'" Chloe read aloud. "The first letter is S."
"Right. Now go to chapter seven," Mark said.
Chloe swiped through the table of contents (navigation menu). She loaded chapter seven and scrolled straight to the bottom.
"The last sentence is 'It was a cold night,'" she muttered. "The first letter is I."
"Keep going," Mark urged. "Chapter twenty-five."
Chloe loaded the page. "The letter is G."
A sudden, intense light sparked in her eyes. She sat up straighter and gripped the metal edges of the phone. She looked exactly like a little kid who just found the missing piece to a fascinating puzzle.
"Next is chapter sixty-one," Chloe said rapidly, her thumb flying across the glass screen. "The letter is N. Then chapter one hundred twenty-one. The letter is A. Then two hundred eleven. The letter is L."
She stopped scrolling. She looked up from the glowing screen, her breathing shallow.
"S, I, G, N, A, L," Chloe spelled out.
She turned her head and looked directly at Mark. Her eyes were wide with realization.
"This is the Signal app," she whispered, looking around the quiet cafe to make sure no one was listening. "The messaging app that is entirely secure because it uses end-to-end encryption. Even the developers cannot view the messages sent between users."
Mark nodded, offering a small, confirming smile.
Chloe did not wait for further instructions. She immediately returned to her puzzle, her thumb aggressively swiping the screen. She hunted down the remaining chapters based on the mathematical sequence Mark had written on the napkin.
She pulled a second napkin from the dispenser and grabbed his pen and wrote down the extracted letters one by one as she found them.
Minutes passed. The ice in their forgotten drinks slowly melted into water.
Finally, she reached chapter 9241 and wrote down the final letter.
She slid the napkin toward the center of the table and stared at the long, continuous string of capital letters.
"S-I-G-N-A-L-I-D-I-N-D-I-V-I-S-I-B-I-L-I-T"
Chloe frowned, tracing the blue ink with her fingernail.
"Wait, hold on," she said, her voice dropping in confusion. "This is exactly twenty-one letters. But it seems the final word is cut off. The letter Y is missing. It spells indivisibilit. Is there a mistake in my extraction?"
"It's not a mistake," Mark said calmly. "Your extraction is perfectly correct."
"That can't be right," Chloe argued, tapping the paper. "Why would the author leave the final word broken?"
"Because," Mark explained, resting his forearms on the table, "the missing Y requires you to go outside the boundaries of the book. Look back at the equation."
He pointed to the first napkin.
"You stopped at x equals twenty-one," Mark said. "If you plug in twenty-two, what chapter does the equation give you?"
Chloe pulled up the calculator app on her phone. She rapidly typed the numbers. Twenty-two cubed, minus twenty-two, plus one.
She hit the equal sign.
"Ten thousand six hundred and twenty-seven," Chloe read from the screen.
"Right," Mark said. "Chapter 10627 represents the missing letter Y. But the book ended exactly at chapter 10000. So the chapter containing the final letter literally doesn't exist."
Chloe stared at the calculator. "Then how does it make sense?"
"Look at the number itself," Mark pointed at the digital display. "10627. That specific sequence is a prime number. Do you know what a prime number is?"
Chloe thought for a second. "A number that can only be divided by one and itself."
"Exactly. It cannot be divided by anything else," Mark said, his voice dropping into a quiet, serious tone. "It fits perfectly with the missing word. The word 'INDIVISIBILIT' is missing its 'Y,' just as the book is missing the prime, indivisible chapter 10627. The missing chapter literally represents indivisibility."
Chloe sat perfectly still. The logic locked into place inside her mind. The sheer brilliance of the hidden puzzle hit her like a blow.
She nodded slowly, a profound respect settling over her features.
"What are you waiting for?" Mark asked, gesturing toward her phone. "Message eT14XjMteCsx. Or do you want to do it later?"
Chloe snapped out of her daze. She looked at him, then down at her device.
She immediately opened her app store and searched for Signal. She downloaded the encrypted messenger, waiting impatiently as the progress bar filled.
The app was perfect for someone like the author who clearly wanted to remain completely anonymous and hide their identity from the public eye.
The installation finished. Chloe opened the application and quickly signed up using a blank profile.
She tapped the new message icon and typed the Signal ID: INDIVISIBILIT.
A blank chat window opened.
Chloe stared at the blinking cursor. Her thumbs hovered over the digital keyboard, but they refused to move and her fingers froze completely.
She turned her head and looked at Mark. Genuine panic flooded her eyes.
"What should I say?" she asked, her voice cracking slightly.
"I don't know," Mark replied, leaning back in his chair. "You have many words you've wanted to say to this person for a long time, right?"
Chloe raised her hands above the table. They were shaking violently.
"Do you see my hands?" she whispered while staring at her trembling fingers. "Mark, I'm so nervous. I can't think straight."
Mark watched her struggle. She was terrified of ruining her one chance to speak to her idol.
"I'll give you space," Mark offered, grabbing his backpack from the floor. "I should go now and give you time to think about how you will send your first message."
He stood up from the chair.
"Wait," Chloe gasped, reaching out to grab the hem of his shirt. "Just stay. Please. If you leave, I'll lose my nerve entirely. I'll type my message right now."
Mark looked down at her white-knuckled grip on his shirt. Chloe's hand was trembling. Mark slowly lowered himself back into the wooden chair.
"Okay," Mark said quietly.
Chloe took a deep, shaky breath. She turned her focus back to the glowing screen and slowly typed out a long, careful paragraph, deleting words and rewriting sentences over and over again. Mark did not watch her screen. He stared out the window, giving her a small illusion of privacy.
Finally, she hit send.
Silence fell over their small table. Chloe placed the phone face up on the wood and stared at it. She looked like she was waiting for a bomb to detonate.
Twenty agonizing seconds passed.
Ping.
Chloe flinched. She grabbed the phone so fast she almost knocked over her empty coffee cup.
She read the response.
***Hello, I am eT14XjMteCsx. You are the first person to get in touch with me. I received your message. I am glad that my book was able to save you. I am flattered, really. Thank you so much for reading my book until the very end. I have a favor, if you don't mind. Please do not share my Signal ID with anyone. This line is reserved only for those who decipher the hidden message I placed in my book. Can you do it?***
Tears immediately welled up in Chloe's eyes. They spilled over her lashes and ran down her cheeks, ruining her careful makeup. She did not bother to wipe them away.
Her hands flew across the keyboard.
***Yes. I promise I will not share this with anyone, eT14XjMteCsx.***
A few seconds later, the author responded with a simple thumbs-up emoji.
Chloe let out a massive, shuddering sigh. The intense nervousness evaporated entirely, replaced by a profound, overwhelming wave of relief and happiness. She clutched the phone tightly against her chest.
She turned to look at Mark.
"I have to go," Mark said, pushing his chair back.
Chloe nodded slowly, her eyes still wet. She did not try to stop him this time.
Before Mark could turn away entirely, she leaned forward and spoke barely above a whisper.
"Thank you."
---
From that day forward, the dynamics of the university open field changed completely.
Chloe brought her fashion group to the grassy area behind the academic building. They did not wear expensive skirts or designer heels. They showed up in plain sweatpants and sneakers, looking entirely out of their element, but they fell into line behind Jake without a single complaint.
Jake looked completely baffled by the sudden reinforcement, but he did not question his good luck. He immediately started drilling the fourteen students on basic footwork.
Mark stood in the back row and blended into the background.
The strategy was working flawlessly. The extroverts and the fashion clique were fully engaged. That left only one fractured piece of the board remaining.
Sheila and the gaming club.
Days passed in a blur of dance practices and university lectures.
The day of the highly anticipated gaming tournament finally arrived.
The late afternoon sun filtered through the heavy blackout curtains of Sheila's massive studio room. Mark sat on an expensive customized gaming chair while playing the chaotic, highly coordinated environment.