Sarah Burks's Arc

Chapter 7 of 13

Sarah traced the coordinates scratched into the metal detector's casing one more time. Three sets of numbers. Three radiation hotspots. She'd assumed they formed a triangle—three points defining a perimeter. But standing here with evidence that someone had monitored this site for years, she recalculated. The leader watched her pull out her analyzer and cross-reference the readings. Sarah's hands moved faster now, checking each hotspot against the factory blueprint overlay. "Not a triangle," she said, her voice tight. "It's a frame. Four corners, not three." She pointed to the detector's scratched numbers. "This fourth coordinate—I never measured it because I stopped after finding three points. I assumed a pattern that wasn't there." The leader leaned closer as Sarah marked the missing corner on her map. The four hotspots formed a perfect rectangle beneath the packaging floor, and at the center sat empty space on every blueprint she'd found. Marvin climbed down from the observation post carrying a rusted metal bracket covered in numbered markings. "Found six of these bolted to the tunnel wall—four arranged in a square, two more near what looks like a power junction." Sarah took the bracket and recognized the etched numbers immediately. Construction markers. Vault-Tec had installed them to mark load-bearing points for something heavy. She followed the tunnel twenty feet and found the source—a massive power shaft still spinning behind a concrete housing, its leather belts worn but functional. The shaft fed directly downward through reinforced flooring that the blueprints claimed didn't exist. The leader touched the spinning drum and pulled back from the heat. "This has been running continuously." Sarah nodded, her throat dry. She aimed her flashlight down through a ventilation grate beside the shaft and saw it—a concrete bunker with rust-stained metal doors, sitting forty feet below in a chamber the factory plans never showed. Faded warning symbols marked the entrance, and fresh scuff marks led from the tunnel they stood in down a hidden access ladder. The leader met her eyes with a new wariness. "Someone's been going down there." Sarah understood what she'd earned through transparency—not just partnership with the Cats, but responsibility for whatever they found next. The person who'd lived here hadn't just monitored the entity below. They'd been visiting it.