The old service tunnel spat Mateo back to the surface through an inconspicuous rusty door in a side alley. If he had obediently followed the guards to the main lobby, they would have confiscated his heavy ring of keys—his only pass into the restricted tunnels.

  He kept the keys, but the original pn had to wait. A father's instinct overruled an engineer's duty: before he could go underground to the gas valves at Pasco, he had to get his family out.

  Avenida Corrientes hit Mateo like a physical, suffocating wave. After the frozen silence of the control room, the roaring street chaos hammered his exposed nerves like a sledgehammer.

  Buenos Aires was melting. The bck asphalt had turned soft, greedily gripping the soles of his boots with every step. The air was thick enough to cut with a knife: a heavy, oily mist of diesel exhaust mixed with the sticky sweetness of roasted peanuts being caramelized in bckened copper pans on every corner. From the open doors of the legendary Güerrin pizzeria, a thick, searing haze of molten mozzarel and charred dough spilled onto the sidewalk.

  Thousands of people flowed past Mateo in a continuous, indifferent stream. Exhausted clerks with unbuttoned, sweat-soaked colrs, tourists seeking refuge in iced frappes, loud barkers at theater entrances. They were all hurrying, ughing, cursing, living their usual Friday lives. None of them suspected that right now, thirty meters beneath their feet, the earth was preparing an exhale capable of snapping the spine of this entire district.

  Mateo walked fast, weaving through the dense crowd. He could feel eyes on him. It wasn't just paranoia—the Ricci family curse, the compulsion to find hidden defects in any system. It was the primal instinct of hunted prey, the hairs on the back of his neck standing on end.

  His hand trembled as he reached into his pocket for his smartphone. He had to call Elena. Warn her. Get Leo from school—or wherever he was hanging out. Jump into the old minivan and head north to their pce in the Tigre Delta, where the soft alluvial soil and water could dampen the shockwaves, far from the city's resonating concrete boxes.

  The phone in his hand came to life, vibrating violently.

  The cracked screen fshed: ELENA.

  Mateo exhaled sharply, nearly colring a passing courier. Mental connection, no doubt. Twenty years of marriage teach you to feel each other's panic across any distance. He swiped the screen and pressed the phone to his ear.

  — “El, thank God! Listen to me carefully. I just got fired. Luis is a complete coward; he’s shaking for his job and ft-out refuses to evacuate the area around Pasco. It’s going to be a disaster. We need to get Leo and...”

  — “Shut up.”

  Mateo stumbled. His wife’s voice was a stranger’s. All the familiar, warm domestic softness was gone. It sounded cold, calcuted, with the metallic rattle of an SITREP. You don't use that tone to discuss family problems. You use it to coordinate artillery fire.

  — “Elena? What’s wrong with the signal?”

  — “Listen to me and don’t interrupt, Mateo. Do not stop. Do not change your pace. And for God’s sake, do not turn your head.”

  His survival instinct smmed on the brakes, making Mateo freeze for a fraction of a second, but the terrifying ice in Elena’s voice forced him to obey. He kept walking, staring straight ahead at the backs of the passing crowd.

  — “What’s happening, El?”

  — “Sigma cleaners are coming for you. A bcked-out SUV, diplomatic ptes.”

  The engineer’s heart plummeted into his stomach, leaving a ringing emptiness in his chest. Sigma. The Consortium’s shadow security service. Officially, they guarded elite construction sites, but among track workers and SBASE veterans, the legends were much darker.

  Everyone underground knew the unwritten rule: if a boring machine hit an unmapped void, or if an engineer asked too many questions about walled-off tunnels from the 1930s, the city police didn't show up. Sigma did. They didn't wear badges or read you your rights. They simply erased people, dissolving them into bureaucratic nonexistence.

  — “They monitor every SBASE communication channel. Your shouting over the open radio about biomechanical resonance... your scene in Luis’s office about the Systole and the rock having a pulse... Luis already sent the report up. They know you’ve stumbled onto the true nature of these tremors. And they know you have Ignacio’s analog blueprints.”

  Mateo felt the asphalt slipping away, but not from an earthquake.

  — “El...” his throat was dry, the words scratching his rynx. “How do you even know about Sigma? Those are just ghost stories from the track crews...”

  A short, scratching silence hung on the line. His brain refused to reconcile the image of his wife with the dry, metallic tone she was using to issue commands. The cognitive dissonance throbbed in his temples.

  — “I’ll expin ter, if we survive,” she cut him off harshly. No excuses. Just orders. “I can't stop them. They’re already in your grid. Forget about me. Save our son—they’re looking for him right now. Dive into the subway. Find the thickest crowd. RUN!”

  The call disconnected with a series of ruthless beeps.

  Mateo had just reached the giant gss storefront of the Frávega appliance store. Dozens of psma screens lined up in the window were silently broadcasting a soccer match. But the engineer wasn't looking at the green pitch.

  In the perfect mirror reflection of the window, he saw the street over his right shoulder. Twenty meters behind him, silently slicing through the flow of yellow taxis, a matte-bck shark was crawling along the curb—a heavy, armored Ford SUV.

  The tinted gss of the rear window was sliding down with a faint electric hum. From the dark void of the interior, it wasn't a hand with a police baton that emerged. A short, matte-bck submachine gun barrel, weighted with a massive suppressor, was pointed directly at Mateo’s back.

  Time turned into thick resin.

  In the reflection, Mateo saw a sales clerk behind the gss zily cover his mouth with a yawn. He saw a little girl at the edge of the sidewalk drop a scoop of pistachio ice cream, watching it fall slowly toward the asphalt. And in the absolute bckness of the muzzle aimed at him, he saw a tiny, angry flicker of fme.

  He dove to the left. Pure, uncontrolble muscle reflex.

  CRACK!

  There was no sound of a shot—the roar of Avenida Corrientes swallowed the suppressor’s pop. There was only the wet, sharp sound of kinetic impact. The massive storefront an inch from Mateo’s ear instantly shattered into a frosted web and exploded into thousands of gss daggers. The nearest TV behind the gss hissed with sparks and went dead.

  The street erupted in screams. Someone shrieked and fell to the sidewalk, covering their head. The crowd surged in all directions, creating instant chaos.

  Mateo didn't remember scrambling off the asphalt. The adrenaline rush erased the pain in his scraped palms. He vaulted over the hot hood of a yellow-and-bck taxi that had screeched to a halt, hearing the dull thud of heavy SUV doors opening behind him and the rapid rhythm of tactical boots hitting the ground.

  Ahead, a saving bck void amidst the blinding neon, gaped the entrance to the Uruguay subway station. Red signs for Line B. Salvation. Or a concrete mousetrap.

  He flew under the vestibule’s overhang, cleared the steel arms of the turnstile in a single leap, ignored the indignant whistle of a clerk, and tumbled down the worn stone steps. Away from the traitorous sunlight. Down into his own world—the pulsing darkness.

  At the same time, a few blocks away, heavy, distorted bass shook the scuffed brick vaults of the underground club “El Teatrito.”

  The air inside was a dense, hot substance. This mixture of human breath, cheap Quilmes beer spilled on the dance floor, and the electric tension of teenage rebellion settled on the skin like a sticky film. Hundreds of teenagers jumped in the primal rhythm of the mosh pit, merging into a pulsing, many-headed hydra under the roar of a local punk band.

  Leo, Mateo’s son, stood at the syrup-slicked bar, greedily gulping air. Thin, pale, with perpetually messy dark hair and the observant eyes of someone who notices details invisible to others.

  To his left, Cobra breathed heavily—a wiry girl raised on the tough blocks of Bajo Flores, with faded purple dreads and an aggressive coral snake tattoo coiling around her neck. To his right, Nico shifted nervously—a sturdy kid from the Vil 31 slums. Dressed in a high-quality knock-off tracksuit, he was used to constantly scanning the perimeter, as if expecting a trap at every second.

  On the hanging monitors above the bar, where they usually pyed psychedelic videos, the image suddenly jerked. The screen was flooded with an arming red. The signature "Pca roja" of Crónica TV:

  URGENTE: CATASTROPHE ON LINE D. MATEO RICCI WANTED ON SUSPICION OF SABOTAGE.

  Leo froze, as if he’d been punched in the gut. From the screen, a pixeted, enrged photo of his own father stared back at him.

  — “This is some kind of sick joke,” Leo managed to say, unconsciously squeezing his pstic cup so hard that ice-cold co spshed onto his knuckles. “What the hell do they mean, saboteur? My father is obsessed with safety! He hasn't slept for two weeks, he covered the kitchen table with charts, kept saying they were pying with fire with that soil. There was an accident, and those bastards at SBASE are just making him the scapegoat!”

  Suddenly, Cobra gripped his elbow hard. Her thin fingers dug into his forearm like steel pincers.

  — “Don't you dare turn around, boludo,” she hissed directly into his ear, her lips barely moving. “Main entrance. Three of them.”

  Leo cautiously cut his eyes toward the coat check. At the double doors, standing a head taller than the sea of punks, were three monumental silhouettes. Dressed in nondescript dark windbreakers and jeans, they looked like alien, sterile elements in this chaos of ripped clothes and tattoos. They didn't nod to the music. They didn't look at the stage. Their heads turned in sync, breaking the crowd into sectors, scanning faces with cold precision.

  Professionals.

  Leo noticed one of them raise a hand to his colr, and beneath the edge of his jacket, the tactical polymer of a shoulder holster shimmered dully.

  — “Cops?” Nico turned pale, instinctively hunching his shoulders, ready to vanish into the shadows.

  — “Hell no,” Cobra spat her gum onto the floor. “Cops are zy and loud. These guys move like wolves. And they're here for you, Leo.”

  — “What for? I didn't do anything!”

  — “They want your old man. And you’re the most effective leverage they’ve got.”

  One of the "wolves" suddenly stopped scanning. His gaze, like a ser designator, locked onto Leo’s face at the bar. The man barked something into the mic hidden in his sleeve and moved forward, pushing through the thrashing crowd with the relentlessness of an icebreaker.

  — “Move!” Cobra barked.

  The three of them dove into the thick of the mosh pit, using the dancers as a human shield, pushing toward the side exits near the stage. Leo risked a look back. The three pursuers had already fanned out, professionally fnking them and cutting off the path to the main doors.

  — “Through the service exit!” Leo shouted, pulling his friends along.

  They tumbled out of the pulsing hall into a dirty, narrow corridor backstage, cluttered with burnt-out amplifiers. A massive iron door with a faded "Salida de Emergencia" sign was wrapped tight in a thick rusty chain with a huge padlock.

  — “?La concha de su madre!” Nico roared in desperation, smming his shoulder into the steel at full tilt. The metal didn't even budge. “It's locked tight!”

  From around the corner, over the bass from the hall, the heavy, rhythmic thud of tactical boots was already audible.

  — “In here! Now!” Cobra jumped to a pile of construction debris and empty beer kegs in a dark dead-end of the corridor and began furiously kicking them aside.

  Beneath the rubble, a heavy cast-iron storm drain cover, encrusted with decades of filth, was revealed.

  — “A sewer?” Nico’s face twisted in a grimace of disgust as he imagined what y below. “Are you out of your mind? It’s a collector down there!”

  — “It’s our only chance, idiot!” Cobra had already jammed her fingers into the holes of the cover and pulled with a strained groan. “Or do you have a burning desire to discuss your civil rights with those guys?”

  Sliding the cover halfway off, Cobra didn't hesitate, slipping feet-first into the gaping bckness.

  Leo turned back. The door at the end of the corridor burst open, smming against the wall. The silhouette of a pursuer loomed in the doorway. In the dim light, the prongs of a police stun gun crackled ominously in his hand.

  Leo grabbed the paralyzed Nico by the colr of his tracksuit, shoved him into the open hole, and jumped in after him.

  As he fell into the darkness, he caught the edge of the cast-iron disk and yanked it shut with all his strength. The heavy cover smmed into pce with a ringing metallic cng, instantly cutting off the music, the light, and the threat—plunging them into a damp, resonating underworld.

  A world that was destined to become their new home.