The Crystalline Fracture

Elias Vance audits high-rises for structural flaws. He knows concrete breathes. It expands. It fails. But the Aurelia Tower was built with experimental self-healing polymer. It was supposed to seal cracks. Instead, a coastal humidity trigger activated an uncontrolled exothermic crystallization. The walls are thickening. The corridors are narrowing. Oxygen is thinning. Elias hears the groaning steel before the doors vanish.
He has one blueprint, a failing flashlight, and a dying structural gap. The building is digesting itself. He has minutes before the walls meet.