Tamsin gave him a look that said she wanted to argue, then sat anyway. Oaks hovered a second longer, then perched on the edge of a rolling stool like an offended sparrow.

  “Starting the first step,” Julie said. On the monitors, the pulse graph softened by a hair. A tiny green LED on the rack changed from steady to heartbeat blink.

  The room didn’t explode. Nothing flared. The vents on the roof might have sighed, but that could have been Ben’s imagination. He held his breath and counted to thirty out of habit and then let it go.

  “Good,” she continued. “Five minutes until the next.”

  Tamsin watched the graph, jaw tight. “Hartmann will fire me for letting you do this.”

  Ben shrugged. “He’ll probably fire you if the place blows up, too.”

  She didn’t argue that, either.

  “Talk to me about your safemode,” Nia said, gentle, almost conversational. “Why is it set to dump into those ring aquifers?”

  Tamsin’s gum finally stopped its march. She frowned at the screen. “Because the model says the ring can take rapid heat — those layers have porosity. We mapped it.”

  “Mapped it how?” Nia asked.

  “Seismic sweeps, tracer gas, old USGS papers,” Tamsin said. “Look, I’m not the architect. I write glue code. Oaks does hardware and the drones. The model came from upstairs.”

  “And upstairs believes the park will behave like the sim,” Nia said. “That’s the problem.”

  Oaks snorted. “It’s math.”

  “It’s a living system,” Nia said. “That math needs humility.”

  CHAPTER 12

  Julie announced the next step. The lines on the graph softened more. The rumble under Ben’s boots faded a shade, like a big cat settling in its den instead of pacing.

  Outside, a floodlight flickered and steadied. A muffled shout came from the pad speakers, then a truck door slammed. The drone buzzes changed into a higher, anxious pitch — maybe operator input, maybe wind.

  “Reggie?” Ben asked.

  “Still a Christmas elf,” Reggie said. “No eyes on me. I can pop this trunk like a jawbreaker if you yell.”

  “Hold there,” Ben said. “We’re easing.”

  Oaks frowned harder at the screen, then at Ben. “You don’t have jurisdiction here.”

  Ben met his gaze and kept his voice level. “Kid, I had jurisdiction the second your pressure wave knocked a hole in the snow. If that hole had been over a boardwalk with tourists, we’d be speaking in past tense. I’m not here to ruin your resume. I’m here to make sure a family from Ohio doesn’t go home with shrapnel where their father used to be.”

  That landed. Oaks’ posture dropped half an inch. Tamsin’s eyes slid away from the graph to Ben’s face and held there a heartbeat too long, as if she’d just noticed the scar by his temple and drawn her own conclusions.

  Julie brought them through the third step. Outside, the drone’s pitch rose and drifted off to the south. The floodlights hummed, but the tone of the pumps dipped — a softer, less angry sound.

  “Pressure in Loop C dropping under their trip-line,” she said. “If the code’s honest, that keeps safemode from autodumping. We keep dialing down. If we can get it to half of their current ceiling, we’ll be out of the danger zone for popping lids.”

  “Once we’re there,” Ben said, “we lock out the control pulses.”

  “Already filed,” Julie said. “I’m ghost-writing a maintenance notice that blames a bad PLC in Pad Two. When their shift lead reads it, he’ll curse and reboot instead of hitting the big button. We like reboots.”

  The bunker door rattled. All heads swung. Ben’s hand found his pistol without thinking, muzzle down but ready. The door didn’t open. The rattling stopped.

  Tamsin glanced at the camera feed for the vestibule — a small square in the corner of the dash — and relaxed a hair. “Wind,” she said. “This slab moves when a gust hits it.”

  “Or someone leaned on it,” Nia said.

  Julie eased them through the fourth step. Ben felt the change in his bones this time — a barely-there pressure behind his eyes letting up, the way a storm front sometimes feels like a headache and then dissolves when rain finally falls.

  “Looking good,” Julie said, and he could hear the breath she’d been holding. “We’re halfway to safe.”

  “Define safe,” Reggie said. “You know, just so I can feel safe.”

  “‘Safe’ means the pressure they’ve been hammering into those shallow layers is back to normal midwinter levels,” Julie said. “Which means if something gives, it’ll be a nasty burp, not a bomb. We’ll still be dealing with scalding water and steam in the wrong places if they’ve weakened a cap, but it won’t be a cascade.”

  Ben let his shoulders drop a notch. Not much, but enough to remind his muscles they existed for something other than clamping down.

  A harsh burst of static cracked over a speaker somewhere outside — the pad PA, distorted and angry. A man’s voice, amplified badly, barked something about “reset” and “override.” Tamsin flinched.

  “That’s Leon,” she said. “Shift lead.”

  “Does Leon like following rules?” Ben asked.

  “He likes hitting things,” she said. “Especially big buttons.”

  Julie slid the next step into place. “If Leon forces a manual override from the pad, he can still trip safemode. It’s not just automatic. The button is real. If he smashes it, my maintenance notice won’t matter.”

  “Then we need to keep Leon busy,” Ben said, and turned to Tamsin. “Call him.”

  She stared. “What?”

  “Tell him the bunker is rebooting the control core,” Ben said. “Make it boring. Use words like ‘checksum’ and ‘latency.’ He’ll leave your systems alone until he has someone to blame.”

  Reggie’s voice patched in. “Oh, I’ve got one! Use the word ‘smorgasbord.’”

  Ben and Nia glanced at one another. Ben shook his head.

  Tamsin hesitated, chewed, and then picked up the radio again. Her voice changed — a practiced cadence sliding into engineer-speak. “Control to Pad One. We’re cycling the core for responses out of spec on the field bus. Don’t touch the pad-side interface during reboot or you risk corrupting the ring. Copy?”

  There was a beat of silence, then Leon came back with a grunt that sounded like a yes wrapped in a threat.

  “Nice,” Reggie said. “Teach me how to say ‘don’t touch that’ in ten-dollar words.”

  “You say ‘running a checksum smorgasbord,’” Tamsin said. “They back away like you said ‘ghost.’”

  Julie brought them down another notch. The graphs smoothed. A tiny red triangle in the corner of the screen changed to yellow, then winked out. The room seemed to exhale.

  “Keep going,” Ben said. “And put a pin in that safemode code. I want it locked behind three doors so nobody can stumble into it while we’re walking out.”

  Julie’s fingers clacked. “Done. I set a password strong enough to make a cryptographer cry and told their audit log that Leon did it. If he has to yell at someone, he can yell at himself.”

  Nia allowed herself a small smile. “Remind me never to cross your wife.”

  “Noted,” Ben said.

  CHAPTER 13

  The door rattled again — harder this time. Not wind. A thump followed, like someone’s shoulder hitting steel. Oaks flinched. Tamsin’s eyes shot to the camera square. A white parka filled it. A gloved hand slapped the lens.

  “It’s Leon,” she said. “He hates reboot messages.”

  “Ben,” Reggie said in his ear, voice low. “You want me to ring the doorbell outside? I can trip a sensor on the far side of the pad. Might pull him off your slab.”

  Ben thought fast. “Do it. Nia, if Leon gets in here, we keep him calm.”

  “You want calm,” Nia said, “you go first.”

  The next minute stretched like thin ice. Outside, somewhere near the generator, Reggie made something beep. A floodlight swung; boots crunched. The camera feed cleared as Leon’s parka moved away.

  Julie slid the last step of the current cycle into place. “We’re at fifty percent of their earlier pressure. That’s my first stop line. Hold here and watch the board.”

  They watched. The lines didn’t spike. The pads stayed green. The drone’s buzz dwindled to a suggestion on the edge of hearing.

  “Okay,” she said. “Now we lock their pulses off and switch to a plain, steady flow. No more hammering. If you have to pull the plug, it’ll be gentler on the system.”

  “Do it,” Ben said.

  A series of tiny LEDs on the rack clicked in a sequence that felt like a lullaby compared to the earlier feral heartbeat. Ben almost smiled and then caught himself. Not done. Not even close.

  “Tamsin,” he said. “Who told you this was a good idea?”

  She stared at the screen. “I write code. I see graphs. I don’t get invited to ‘good idea’ meetings.”

  “And Oaks?”

  “Drones,” the young man said stiffly. “I keep them flying.”

  “Do the drones carry weapons?” Nia asked.

  “Cutters and spot welders,” he said. “And little lasers for rangefinding.”

  “Little lasers can blind people,” Nia said.

  He didn’t answer.

  Ben looked back at the door. The camera showed an empty vestibule, but his skin said someone would be through it soon with questions and maybe a rifle. He needed the next move ready before the questions walked in.

  “Jules,” he said. “Worst case — if Leon hits the big button and trips this ‘safemode’ anyway — what happens?”

  “In plain terms?” she said. “It opens a bunch of side doors at once. Steam and gas rush into places we can’t see. If the ground is weak in that ring, you get violent steam blasts popping off like a string of fireworks. Could still be survivable if nobody is standing in those spots. But with lights and drones and curious men in white parkas? Bad day.”

  “So we keep Leon’s hand off the big button,” Ben said. “We keep easing the pressure. And if he charges this door, we make sure he decides he has better things to do.”

  Nia’s gaze flicked to the workbench. She plucked up a roll of bright orange tape and tore a strip. “Give me something to label ‘Do Not Touch.’”

  Ben pointed to a harmless breaker panel on the wall beside the racks — one he’d noticed earlier labeled “Aux HVAC.” Boring. Official-looking. Nia stuck the tape on it and wrote in fat marker: CRC CHECKSUM IN PROGRESS — DO NOT TOUCH.

  “Magic word,” Tamsin said, and for the first time there was a ghost of a grin at the corner of her mouth.

  The inner door vibrated with a human knock. Three short, one long. Ben stepped to the side of the frame and lifted a hand to Nia: Let me talk first. He cracked the door an inch.

  A face filled the gap — square jaw, frost in a trimmed beard, skin flushed with cold and temper. “What’s going on in there?” he demanded. “My pad’s screaming.”

  “Core cycling,” Ben said, adopting Tamsin’s cadence as easily as he’d once put on his ranger voice. “Field bus returns are out of spec. If you touch your controls you’ll corrupt the ring. Give us ten.”

  The bearded man frowned. “Who the hell are you?”

  “Control,” Ben said, because half of confidence is saying it like it’s obvious.

  “I don’t know you,” he said. He tried to shoulder the door. Ben let the slab give an inch, then stopped it with his hip and a hand braced low — friendly, not aggressive.

  “Leon,” Tamsin called without standing. “It’s me. Tamsin. We’ve got a ring defrag running. If you toggle anything on the pad you’ll brick the PLC and I’ll make you write the incident report.”

  That landed harder than any threat Ben could have invented. Leon squinted at the gap, looked between Ben and the room beyond, saw Tamsin at the console, and grimaced like a man who’d bitten a lemon. “Five minutes,” he warned. “Then I’m coming in.”

  “Five is perfect,” Tamsin said.

  Leon stomped away. The door shivered, then stilled.

  Ben closed it gently. Nia let out a breath he hadn’t realized she was holding. Oaks muttered something under his breath that sounded like an apology to the universe.

  “Ben,” Reggie whispered, “Christmas tree is wrapped. If you need the lights out, I’ve got a shiny red button.”

  “Hold that thought,” Ben said. He looked at the graph. Stable. Not safe, but no longer flirting with stupid. He looked at Nia. Ready. He looked at Tamsin and Oaks. On the edge of belief.

  “Jules,” he said, “give me the next phase.”

  “We hold this level for fifteen, watch for a rebound,” she said. “If it stays flat, we step down again. After that, we lock the valves, kill the pulses in code, and walk away. Rook is circling on fuel. Weather’s still our friend.”

  “Copy,” he said. He rubbed the scar near his temple, just once, the way he always did when he felt the next choice looming. Then he squared up to the room.

  “We’re not out of the woods,” he said. “But we’re heading toward the trees we know.”

  Outside, the drone’s sound faded into the wind. Inside, the bunker hummed and breathed. And for the first time since the floodlights snapped on, the park felt less like a trap and more like a giant exhale waiting to happen — if they could keep foolish hands off the wrong switch.

  CHAPTER 14

  Ben let his shoulders drop the smallest degree and checked the clock. Five minutes since Leon’s last knock. Ten since the little blow behind the drain field. Forty until their earlier guess for the trip-wire.

  “Hold it steady,” Julie said in his ear. “I’m watching for a rebound. If the rock tries to push back, we pause. Otherwise we creep down again.”

  “Copy,” Ben said.

  Nia circled the room with a ranger’s restlessness — reading labels, memorizing panels, testing the swing on the breaker cover she’d christened with a warning tape. Tamsin stayed at the console, eyes on graphs. Oaks perched, sullen, but his glance kept jumping to the door.

  Outside, the wind found its night voice. It knocked ice crystals off the antenna mast and threw a handful at the vestibule door with a sound like birdshot. Somewhere farther off, a floodlight buzzed into a new pitch and died, then relit, then steadied. Beyond that: the unmistakable clink of chains on a tracked vehicle and a distant PA squawk dragging across the trees.

  Reggie came over comms, low and cheerful, which meant he was nervous. “Christmas tree all wired. I’m tucked under a tarp with the world’s saddest view of a generator. Leon just walked past me mumbling something about checksum demons. Love that for us.”

  “Keep playing elf,” Ben said.

  The monitors blinked — once, twice — like someone had dimmed the room and turned it on again. Julie sucked in a breath. “Heads up. I just saw an upstream handshake.”

  “In English,” Ben said.

  “Someone outside your little cluster gave the brain a pat on the head,” she said. “Looks like a command ping rolling across your network from a different path. Like… like a boss walking in and saying, ‘Daddy’s home.’”

  Ben’s skin went cold in the warm room. “Hartmann?”

  “Or his architect,” she said. “Whoever it is, they’re about to push a new set of instructions.”

  Tamsin’s jaw tightened. “Remote patch?”

  “Firmware or script,” Julie said. “They’re trying to reassert control. I can stall a couple of cycles, but if I keep batting it away they’ll notice a fight and force a reboot from outside your box.”

  Oaks brightened in offended pride. “You can’t push firmware through a field bus. It’ll brick the — ”

  “It’s not the bus,” Julie said. “It’s your other pipe.”

  Ben looked around. “Other pipe?”

  Nia pointed to a thin, yellow cable coiled like a garden hose and clipped along the ceiling. “Not power. Not fiber. Microwave relay tied to a mast. Subtle. Microwave dishes catch snow, so they ran a low-profile panel. Your ‘other pipe’ is line-of-sight.”

  Tamsin chewed, thinking. “Uplink goes to a relay on Pad Two. Then out to a hilltop node behind Norris. If they hit that button, they can shove an update down past anything we’ve done.”

  “Can you kill the microwave,” Ben asked, “without flipping every alarm you own?”

  Tamsin shrugged with an engineer’s fatalism. “If I pull that cable, the software screams and tries the backup route, the fiber you saw in the trench. It will keep trying both.”

  “Then we cut both,” Nia said simply. “We break their internet.”

  Oaks laughed short and bitter. “You don’t get it. Redundant paths are the whole point. You can bleed my uplink, and the box will try to call home through the phone line.”

  “Then we snip the phone line, too,” Nia said.

  “Julie,” Ben said, “can you hold the patch for two minutes?”

  “I can kick the can for three before they pop the hood and push past me,” she said. “The second they notice me, they’ll jam a command that locks us out. But they’re already suspicious, I’d guess.”

  “Then this is a wire-cut,” Ben said. “Short and unglamorous.”

  He stepped onto the workbench, grabbed a ceiling clip, and pulled the yellow cable down. It came free with a squeak and spilled into his gloved hand. Tamsin grimaced and held up a utility knife in silent consent. He sawed through the insulation, cracked the connector, and separated the ends. A tiny light on the panel above the rack went from green to red. Somewhere, a quiet process wrote an angry line into a log.

  On the screens, nothing changed — at first. Then a small icon in the corner shifted from “MW LINK: OK” to “MW LINK: FAIL.” It blinked three times and flipped to “RETRY.”

  The monitors flickered again. Julie hissed. “They felt that. They’re pushing harder on the other path.”

  “The fiber,” Nia said.

  Ben was already at the back of the racks. The blue cable she’d pointed out earlier ran along the wall into a junction the size of a paperback. He popped the cover, yanked the connector, and felt the faintest tremble in the room as something outside the bunker decided it was alone for a second.

 

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