The greasy smell of the La Serenata alleyway hit Lena like a physical blow as she burst through the service door, her worn sneakers skidding wildly across the frozen asphalt. Her chest burned with a familiar, searing agony, the cold February air tearing at her lungs with every jagged breath. She had broken the cardinal rule of her eight-month exile: she had stopped being a ghost.

Warning: Perimeter Breach. Sector Four Sub-Level Compromised.

The automated computer voice echoed mechanically through the hallways as heavy steel blast doors slammed shut across the facility, isolating the upper trauma wards from the secure underground labs.

Lena grabbed her secure satellite phone off the desk, dialing Marco’s direct emergency frequency with a single thumb press.

"Marco," Lena said, her voice sharp and commanding. "We have a Class-One security breach. Not local syndicates—federal black-ops. They're hitting Sector Four."

"I know," Marco’s voice came back instantly, cold and steady amid the sound of automatic gunfire echoing in the background of his end. "They bypassed our surface security grid in under ten seconds. They're using military-grade EMP charges."

"They're after Clara," Lena said, glancing at Dr. Guzman’s sister, who was frantically packing the biological ledger back into its lead cylinder. "They want the neural regeneration data."

"Lock down your lab and stay inside the reinforced vault," Marco ordered. "I'm coming down with the cleanup crew."

"No, Marco, listen to me," Lena argued, watching the security monitor as thermal imaging displayed a dozen tactical figures cutting through the heavy steel blast doors with a plasma torch. "If they breach the core, they'll destroy the entire facility just to erase the evidence. We have to flush them."

"Flush them how?"

"The emergency oxygen scrubbers," Lena said, her eyes locking onto the master ventilation schematic on her desk. "If we overload the hyperbaric chambers in Sector Four and ignite the nitrous lines, we can blow the lower access tunnel without compromising the primary medical vault."