I flipped down my visor and let the HUD come into focus.

“Kill the lights,” I whispered. The stairwell plunged into darkness. The helmet’s night-vision kicked on, and the stairwell coalesced in shades of green and black.

“Check. Alpha is go.”

“Bravo, go.”

“Charlie, go.”

I set the shotgun’s stock against my shoulder. “Go go go!” I took the final flight of stairs, Stern and Rosen behind me, faceless behind their visors.

35th floor. I leaned against the door-jamb, listening, then nodded to Stern. He came forward, kicked the door open, and I stepped out, swept the room with my shotgun.

Something bounced across the floor, bumped my heel as it rolled between my legs. Went into the open door behind me.

“Shit! Get down!”

The grenade exploded with a hollow thump behind me, amplified by the cramped stairwell. The blast lifted me from my feet and sent me flying, ears ringing.

“Alpha! Officers down!”

I jumped to my feet, shotgun held ready. I spun towards a blur of movement on my left.

“N.O.C.A.! Freeze!”