A faint cry came from behind the ballroom wall while champagne glasses clinked only yards away.

The contrast between the opulent, glittering ballroom and the silent, utilitarian servant corridors was jarring, yet profoundly familiar. I moved quickly, my expensive heels making virtually no sound on the thick carpeting. I navigated the labyrinthine hallways with the precise, practiced efficiency of someone who had spent her entire adult life learning how to be invisible in the homes of the wealthy.

"Take the next left," Luis instructed through the earpiece. "You should see a heavy steel door at the end of the hall. That is the entrance to the sub-basement. There is a single camera pointing directly at the keypad."

I rounded the corner and stopped immediately. The steel door was imposing, completely incongruous with the elegant residential architecture of the surrounding house. Above it, a red light blinked steadily from a high-definition security camera.

"I see the camera, Luis," I whispered, pressing my back against the wall to stay out of its immediate field of view. "Can you loop the feed?"

"Already done," Luis replied, the sound of rapid typing echoing over the line. "I hacked into their internal network using a vulnerability in their smart-lighting system. The security guards in the control room are currently watching a pre-recorded loop of an empty hallway. You have exactly four minutes before the system runs a diagnostic sweep and realizes it has been compromised. Go."

I stepped out from the wall and approached the steel door. My heart hammered against my ribs, a frantic rhythm of adrenaline and terrifying anticipation. I pulled the cloned keycard from my clutch purse and pressed it against the biometric scanner panel.

For a horrifying second, a red light flashed on the panel, and the machine emitted a low, angry beep.

"Luis," I panicked softly. "It rejected the card."

"Hold on," Luis said, his voice tight with tension. "Mercer upgraded the encryption protocol this morning. I am pushing a bypass code to the scanner remotely. Try it again. Now."

I swiped the card a second time. The panel flashed a brilliant, welcoming green, and the heavy internal deadbolts disengaged with a loud, satisfying clack.

I grabbed the heavy metal handle and pulled the door open, stepping into the freezing, dimly lit stairwell that led down into the sub-basement. I pulled the door shut behind me, plunging myself into a profound, suffocating silence. The music from the gala above vanished entirely.