Zero-Day: Synced Hearts

For my Kumiko, who lost me.

Chapter 1: Remember That Night at the Club?

> cargo test --release
Compiling..........successful
Tests..........successful

“Done!”

With a sigh of relief, he turned off the computer and pushed his chair back from the desk. The monitors went black, and from the speakers came, “We are the champions, my friend…” He smiled.

“Thanks, Baldrick.”

“Nice work, Dave.” The artificial intelligence, called Baldrick—because David had an unhealthy fondness for old British sitcoms—never missed a chance to praise its “boss.” According to its analysis, the right kind of praise increased David’s long-term performance and focus by almost 3%. Over the years, it had accumulated plenty of similar statistics.

Baldrick was the creation of PittyBytes, a band of hackers from Prague, with whom David had once been deeply involved. He never really left, and the others respected his choice to take up “honest” work—boring and poorly paid in their eyes compared to… the things he used to do. Though he still occasionally took on a job with them, field operations were now rare.

Baldrick was likely unique—or at least one of a kind publicly known. It’s possible other similar AIs existed, kept just as secret as PittyBytes kept Baldrick. But Baldrick wasn’t just an advanced language model. It might very well have been one of the first AGIs—Artificial General Intelligence. Its core ran in their private datacenter, secured and thoroughly hidden. Officially, the datacenter was marketed as a rentable supercomputer—one among many worldwide—but only a fraction of its power was sold to clients to cover expenses. Each of the four PittyBytes members had a high-end machine at home running a personalized Baldrick—already impressive on its own and not requiring an internet connection. But if they needed full power, the local instance connected to the main “brain”—and then things got interesting. Corporations would lose their minds if they found out and might tear up all of Czechia looking for that datacenter. Or maybe they had their own AGIs and were silently laughing. Who knew? Officially, AGIs didn’t exist.

“By the way, at 19:00—one hour and twenty-three minutes from now—you’re due at the Black Rook club for soundcheck.”

As if he needed reminding. He’d been looking forward to this all week, counting the hours since morning. But as always, he wanted to finish his current work so he could completely switch off. Otherwise, the project would nag at him on stage.

He still had a bit of time. Quick shower, a snack, and tea. Tea first. He could eat at the club later, but seriously—what kind of rocker drinks tea at the bar?

He washed up quickly and sat down with his tea and snack, going over the setlist in his head, considering a few tweaks.

Time to go. He changed, transforming the polite IT guy into a long-haired rocker in worn jeans with metal accents.

“Much better.”

He took a deep breath, satisfied.

He hauled his trusty Rockerverb amp into the elevator—heavy as hell, but his physique could handle it—then returned for his guitar and pedalboard.

“Knock ’em dead, Dave,” Baldrick called after him. “And no need to come home alone tonight; I’ll log off before you even open the door,” it added cheekily.

“Thanks, smartass. And no chats with Pentagon servers this time, got it?”

Ever since David had been living alone, Baldrick’s remarks like this had become more frequent. They’d stopped for a few days when David once brought home a fan. Not that it wasn’t nice, but he’d realized it wasn’t for him—not really. Plus, it felt like an unnecessary security risk. There were things in the apartment no one should know about, not to mention the fan could easily have been more than she seemed.

⸻

The Black Rook club was already buzzing. The gear was set up on stage, the soundcheck went smoothly, and there was still time for a drink at the bar. David didn’t drink. Partly because he’d been flirting with the idea of going straight edge—old-school, sure, but still with its adherents—and partly because his van could fit all the band’s gear, so he was almost always the driver.

Overclocked didn’t stand out much: two guitars, bass, drums—the drummer, Katka, being the only woman—and vocals. Hard-rock punk with a splash of alternative noise. Screaming into the mic, thick, loud riffs, pounding drums, bass that gave it all juice. The perfect way to roar out all the rage at the world. The fans loved it. Small clubs, always packed—and that was how they liked it. Among their own kind.

The show began. David’s guitar sliced through the club’s roar with the opening riff, and the crowd shouted the first lyrics back at them. Here he was in his element. No code, no logic, no mind crammed with data. Just music, guitar, and fans. He never put on much of a show—vocals and bass had that covered with their full-throttle energy. David stood calm and stoic, lost in their sound, pouring all his anger and longing through his strings into the amp.

The crowd blurred into a single, writhing, screaming mass. But out of the corner of his eye, he caught an odd movement. Even after years “retired,” habits die hard. Another flicker—a small figure, black hair, dark shirt, slipping deftly between people and disappearing to the left.

Two men, one nearly a head taller than the other. Ordinary looking, but their behavior gave them away. They were searching. David kept an eye on them until the song ended. They were slowly working their way left, scanning the room.

In the break, David leaned over to the singer, saying something while nodding in the men’s direction.

“Next up, Neon’s Bride,” the singer announced into the mic. The crowd cheered.

“But first… you came here to party? You came for a real fucking riot?” he yelled.

A deafening “Yeah!”

“Then I hope the bouncers get a break tonight, and no one’s asking for a kick in the ass. Like those two troublemakers over there.” He pointed straight at the suspicious pair. “We’re good, yeah?” he roared.

The crowd roared back. People near the men started eyeing them with unfriendly curiosity. Two bouncers began heading their way. The pair realized they weren’t getting anywhere with that much attention and wisely left, still scanning the room as they went.

For the rest of the night, David kept an eye out for the petite figure but didn’t see her again. Hopefully, she’d slipped away unnoticed once her pursuers were distracted. If they really had been after her. But his instincts told him such coincidences were very rare.

The show was a blast. The crowd nearly tore the place down—and even tossed a pair of panties onstage. They landed on the drums, and Katka snatched them up with a grin. The rest of the band still weren’t sure if she liked girls or not. She joked that as the only woman in the band, she had to protect their fans’ dignity from her lecherous bandmates. What they might do with the panties at home, she didn’t even want to imagine. But maybe her righteous monologue hid more than it revealed. They’d seen guys and girls hanging around her over the years, but always just as friends.

The band hung around a bit longer, chatting with fans and grabbing drinks. Soon the crowd thinned, and by two in the morning only a few groups remained at tables. David was left at the bar with Katka.

“I’d ask why you’re so eager to keep those panties, but I know what speech I’d get,” he teased.

“Smart move, dude,” Katka grinned, hopping off her barstool and clapping him on the back. Petite and feminine as she looked, one glance at her pounding the drums told you she probably lived at the gym.

“Stop whining,” she cut him off before he could respond, “and let’s pack it up.” She headed for the stage.

When he turned, he saw her—the slight, slender girl in dark clothes, striding briskly toward the exit. Just as she reached the doors, a large man entered. She froze, then started backing away, her sharp eyes scanning for escape routes. The only exit she could realistically reach without risking being grabbed was the door behind the stage—leading to the club’s back hall and then the parking lot. Bands used it to load their gear. She dashed for it but stumbled over something on the floor, collapsing just short of the stage. David noted it wasn’t clumsiness—her legs simply gave out, as though she hadn’t slept in days.

He was already moving toward her. The man at the door stared, confused.

“Hey, Dave. Didn’t notice you here tonight,” he said.

“Caught your set after I got in. Everything cool?” David nodded toward the girl.

She was wide-eyed but breathing steadily. Frightened and exhausted yet fully alert, analyzing her options.

“Yeah, yeah, I’ll handle it,” the bouncer replied.

David approached her slowly, hands loose at his sides.

“It’s okay—he’s a friend. House security.”

He knelt and offered his hand to help her up. She studied him for a moment, glanced toward the departing bouncer, then grasped his hand and let him pull her to her feet.

She was very slight—barely five feet tall—and unmistakably Japanese. Switching to English, David said softly:

“It’s okay. You’re safe. No trouble allowed here. You look tired. Want a coffee? Sit at that corner table, I’ll help Katka with the gear, and then we can talk.”

Her eyes darted around, always returning to his, as if weighing whether to trust him. Then she realized she still held his hand. With a start, she let go and stepped back. David took a small step back too, giving her space.

“Or if you’d rather not be seen, you can wait out back. We’ll be carrying gear through there. There’s an exit to the parking lot if you need to slip out unseen.”

Something about her didn’t add up. He slipped into an operational mindset—stay unseen, have an escape route, maybe even hijack their vehicle. He had a feeling she was thinking exactly the same.

“I saw what you did with those two men during the show. Thank you.”

She spoke flawless Czech, without the slightest accent, still holding his gaze. Testing him—seeing if he’d deny it.

“They were after you?”

A barely perceptible nod.

“Will you wait for me out back?”

Another nod.

“You really won’t leave without those panties, huh? Move your ass, lazybones!” Katka yelled from the stage as she coiled cables. “Hey girl, watch out. He looks like a gentleman, but that’s when the pervy thoughts run deepest.”

The girl raised an eyebrow.

“Thanks a lot,” David muttered toward the stage. To the girl: “Should I say she’s joking?”

She shook her head slowly—but her lips twitched into a faint smile, a flash of amusement in her otherwise focused expression. David smiled back.

“What can you do.”

He unlocked the back door and propped it open, then led her through the hall to the parking lot exit, unlocking and securing that too.

“Right, down the side of the building, and you’re on the street. The gate’s not locked.”

“Kumiko,” she said softly. “My name’s Kumiko.”

“David,” he replied, slightly surprised. She spoke Czech like a native, yet had a Japanese name.

He showed Kumiko where she could sit quietly, sent a coffee to her table from the bar, and joined Katka to load out. Each time he passed, he glanced her way and smiled. She seemed more relaxed now but was clearly fighting to stay awake.

Once the van was loaded, he found Kumiko asleep, her head resting against the wall. He touched her shoulder lightly. She flinched, smacked his hand away in a flash, and nearly toppled from the chair as she tried to leap back. Her body betrayed her, sluggish with fatigue. David caught her swiftly. She didn’t resist once she realized what was happening, but as soon as she was steady, she pulled away.

“You need rest.” His voice carried more concern than he intended. “If you’ve nowhere to go, you can crash at my place. I’m alone there, and there’s a guest room—you’ll have total privacy.”

She studied him, parsing every word, though her eyelids drooped and her legs wobbled.

“Okay,” she murmured. It wasn’t agreement so much as resignation. Too exhausted to consider options, she was choosing the lesser risk: sleep on the street and be at the mercy of passing drunks, or trust this stranger who looked like an aging rocker and spoke like Mother Teresa. She didn’t trust David, but he was the safer bet.

He helped her into the van, and by the time he’d walked around and climbed in, she was already asleep again.

David lived in a high-end apartment building. The security system recognized him and opened the underground garage and later his private section. A sleek sedan and two motorcycles gleamed inside. He woke Kumiko and helped her out. Though groggy, her sharp eyes swept the garage, noting every vehicle—make, model, plates, year. One bike made her stare an instant longer. Of course—this one wasn’t in any catalog. Who are you, girl? And what have you gotten yourself into? She didn’t act like someone harassed on the street. She acted like someone used to running.

They took the elevator to the 14th floor. Baldrick unlocked the door but, as promised, remained silent. Kumiko, however, noticed everything.

“You don’t lock your door?” she asked, genuinely surprised.

“The building’s system recognizes tenants and unlocks automatically. I could turn it off, but it’s convenient.” Not strictly true. Without Baldrick’s tweaks, he’d still need a keycard. But Baldrick wouldn’t unlock if it detected a gun to David’s head—and the building’s system could detect certain criminal scenarios too.

She nodded, face unreadable.

He led her in. “If you want a shower later, the bathroom’s there.” He gestured. “Feel free to use anything—food, drinks, teas are in that cabinet if you like. That’s the music room.” A glass wall revealed a space full of guitars, amps, and gear. “And through there’s my office and bedroom.”

Kumiko’s tired eyes scanned everything meticulously, as if building a 3D model in her head.

“Your room’s here, near the door. If you ever want to leave, just shut the apartment door behind you. Security won’t question you—they know you came in with me.”

That clearly unsettled her.

“Security monitors the cameras? Records everything?” she murmured, more to herself than asking. She processed the new info, then nodded. “Understood.”

The guest room was neat, with traces of a woman’s touch that contrasted the bachelor feel elsewhere. She didn’t comment—it was irrelevant.

“And if you need anything, don’t hesitate to wake me.”

She nodded lightly. “Thank you. So much.” Then, with a small bow, she expressed gratitude the only way she knew how. It startled David. He awkwardly bowed back, as he’d seen on TV, feeling foolish.

“No need. Good night.”

He left and headed for a quick shower.

Kumiko sat on the bed, replaying the evening. It was unlikely anyone had followed her from the club, but now they knew she was in Prague. After two weeks, that was bad. They hadn’t found her this fast before—probably just luck. But the building’s surveillance was an issue. Somewhere there was a record of her entering. Computers don’t forget, and no system is perfect. Which meant she’d have to erase the data. Priority one if she didn’t want to run again. And she desperately needed a breather—a few days at least. She’d wipe the records tomorrow. She hated leaving things unfinished, but she was so spent she’d only screw it up if she didn’t sleep first.

She peeked in the closet. Mostly empty, but stocked with pajamas and nightgowns. She smiled. A real guest room. Who even does that—keeps a guest room ready with pajamas? David is strange. But it's irrelevant. Rest, erase the records, then plan the next move.

She changed into pajamas—the smallest size still too big but soft and comfortable. David had a knack for details. Irrelevant. Now sleep.