"That's it," I whispered, pointing toward the far end of the corridor where a door marked "Technical Operations" stood slightly ajar. "Whatever's generating those calls, it's in there."
Rachel nodded. "How much time do we have before more guards show up?"
"Probably not long," I said, checking my weapons and the recording equipment. "Whatever intelligence runs this place knows we're here now. It'll be mobilizing every defense it has available."
We moved toward the Technical Operations door, our footsteps echoing softly in the corridor despite our efforts at stealth. The humming sound grew more pronounced as we approached, and I could feel it vibrating through the building's structure rather than just through the air. Whatever was generating that frequency had serious power behind it.
