Thirty-two weeks pregnant, I watched my husband walk into his family’s Christmas party with another woman wearing the diamond necklace he had secretly purchased during a hotel stay. Sixty guests were watching when I finally told him, “Since you brought someone, I brought someone too”—but Matthias had no idea that his infidelity was no longer the most dangerous secret I had uncovered.

Blackness crashed over the grand hall like a physical blow.

Instantly, shrieks of terror tore through the dark. The sound of crystal glasses shattering against hardwood, bodies colliding with antique furniture, and the frantic shuffling of sixty panicked people turned the stately Christmas gala into a stampede.

"Nobody move!" Marcus Vance’s voice cut through the chaos like a whip, loud and authoritative. "Stay where you are! Drop to the floor!"

"Serena!" Matthias’s voice was high-pitched, hysterical, somewhere to my left. "Serena, where are you?!"

I didn't answer him. Nine years in the trauma bay had taught me that in a mass casualty event, the person screaming for their own survival is the one most likely to drag you down with them.

I dropped to my knees immediately, my right arm curling around my belly, shielding my unborn daughter from the blindly trampling boots of Greenwich’s elite. My swollen joints screamed in protest as my knees struck the cold marble, but the surge of adrenaline drowned the pain.

A heavy hand gripped my shoulder.

I recoiled, preparing to drive my elbow into the assailant’s ribs, but a low, calm voice spoke directly into my ear. "It’s Marcus. I’ve got you. Stay down."

A tactical flashlight snapped on, its narrow, high-intensity white beam slicing through the choking blackness. Marcus was crouched beside me, his body forming an impenetrable wall between me and the stampeding crowd.

"The south carriage house," I whispered, breathing through the Braxton Hicks contraction that had suddenly clamped down across my lower abdomen. "Marcus, the accelerant. If the power was cut from the main breaker, the automatic transfer switch to the generators will trigger an electrical arc in the cellar."

Marcus’s flashlight beam swept toward the entrance. "The auxiliary line. Fiona knew the layout."

Across the room, the beam illuminated a nightmare.

Richard Hensley was no longer standing near the fireplace. Neither was Fiona.

Matthias was on his hands and knees by the grand piano, his tuxedo jacket torn, his face smeared with soot and blood where someone’s heel had caught him in the scramble. He looked up into the glare of Marcus’s flashlight, his eyes wild and unhinged.

"They took the keys," Matthias babbed, pointing a shaking finger toward the rear corridor that led to the wine cellar and the underground garage. "Hensley had a master keycard to the service tunnels! He locked the heavy iron fire doors from the inside! We’re trapped in the main hall!"

"What?" Eleanor Dre’s voice wailed from the darkness. The imperious matriarch was huddled beneath a portrait of her late husband, her diamond jewelry glittering in the flashlight beam like frozen tears. "The service tunnels lead to the old fallout shelter! The foundation walls are two feet of reinforced concrete!"

"Which means if a fire starts in the basement, this entire floor becomes a furnace," Marcus said grimly.

He reached into his tactical vest, pulled out a heavy-duty two-way radio, and keyed the mic. "Team Two, this is Vance. Status on perimeter."

Static. Pure, hissing white noise.

"Jammer is still active," Marcus muttered, his jaw setting into hard, dangerous lines. "The storm is providing complete cover. Local fire and rescue won't even see the smoke until the roof collapses."

"I can get us into the service tunnels," I said, rising to my feet using Marcus’s arm for leverage. My knees shook, but my voice was completely steady.

Matthias scrambled to his feet, lunging toward me. "Serena, please! Don't listen to him, we have to break the front windows—"

"The front windows are three-ply hurricane glass, Matthias, you installed them yourself three years ago to stop paparazzi," I snapped, pulling away from his grasp as if his touch were toxic. "If we stay in this room, we suffocate from carbon monoxide within twenty minutes."

"How do you know how to open the tunnel doors?" Marcus asked, keeping his flashlight pointed down the corridor.

"Before your father died," I looked at Eleanor, whose face was pale and slack with horror, "he showed me the manual bypass for the pneumatic locks. He didn't trust Matthias with the estate’s structural schematics. He thought his son was too soft. Too careless."

I took a deep, agonizing breath as another contraction rippled through my belly. *Hold on, baby girl,* I thought, pressing my palm against the burgundy velvet. *Just a little longer. Mom’s got this.*

"The bypass is behind the breaker panel in the pantry," I said to Marcus. "But Fiona and Hensley went that way. If they’re setting the timer on the accelerant, they won't leave witnesses."

"Then we don't give them a choice," Marcus replied, drawing his Glock 19 and racking the slide with a clean, metallic *clack*. "Stay behind me, Serena. Matthias, if you want to survive the night, get your mother and the guests toward the north conservatory. The glass there is single-pane. If the air gets thin, smash it with the bronze statues."

Matthias stood there, completely paralyzed, looking at the woman he had cheated on, the woman he had planned to discard, leading the rescue effort while he held nothing but empty hands and ruined pride.

"Serena..." he choked out, tears finally spilling down his cheeks. "I'm sorry. God, I'm so sorry—"