For fifteen years, I trained Marines to turn nothing but their bare hands into deadly weapons. I was the master hand-to-hand combat instructor for Force Recon and MARSOC Raiders at Camp Lejeune.

Before the laughter even faded from Vance’s lips, I moved.

I didn't turn around. I reached behind my back, grabbed the heavy iron deadbolt of the gym's main industrial entrance, and slammed it shut with a loud, metallic CLANG. I turned the secondary brass lock and dropped the heavy security bar into place.

The laughter died instantly.

"What the hell are you doing, old man?" Vance growled, his eyes narrowing as he stepped forward.

"I'm locking the doors," I said, my voice dropping an octave into pure combat frequency. "None of you are leaving until I am satisfied."

The largest of the four heavyweights—a 250-pound powerlifter named Brick with taped knuckles—snorted and lunged at me with a telegraphed right hook. To a street brawler, it looked terrifying. To a master combat instructor, it was moving in slow motion.

I didn't block. I stepped inside the arc of his punch, slipping past his guard. My palm struck his chin upward with precise kinetic force, snapping his head back. Before he could recover, my elbow drove straight into his sternum, knocking every drop of air out of his lungs. As he doubled over, gasping, I grabbed the back of his neck and slammed his nose straight into my rising knee.

CRACK.

Brick collapsed like a sack of wet concrete, groaning in his own blood on the black rubber mats. Total elapsed time: two seconds.

The remaining three fighters froze, their confident expressions melting into pure shock.

"Who's next?" I asked softly, taking a half-step forward.

Dustin’s face paled, but his pride overwhelmed his fear. "Get him! All three of you at once!"

The two sparring partners rushed me simultaneously. The one on the left threw a low kick aimed at my knee; the one on the right attempted a double-leg takedown.

I caught the kicker's heel in mid-air, twisted his foot counter-clockwise to destroy his balance, and shoved him hard into the man attempting the takedown. They collided in a tangle of limbs. I stepped over them, driving a heel-palm strike into the second man's collarbone. The bone snapped with the loud sound of a dry branch breaking.

He shrieked in agony, rolling onto his side, clutching his ruined shoulder.

The kicker scrambled backward on his hands and knees, terror in his eyes. "He's crazy! Man, he's not human!"

Vance reached behind the counter and pulled out a heavy wooden baseball bat. His massive neck veins bulged as he gripped the handle. "I don't care who you used to train, old man! You don't come into my gym and trash my fighters!"

Vance swung the bat toward my head with full killing intent.

I stepped directly into the attack rather than trying to back away. The bat whistled past my ear by millimeters. Before he could reset his hips for a backhand swing, I drove the butt of my hand directly into his throat, trapping his trachea. Vance gagged, dropping the bat as he choked for air. I swept his front leg out from under him and brought him crashing to the floor, pinning his massive frame with a knee buried deep into his solar plexus.

I leaned down, my face inches from his purple, gasping face.

"You taught him how to hurt women," I whispered chillingly. "You gave him power without discipline. That makes you just as guilty."

I struck a pressure point behind his ear, and Vance's eyes rolled back. He went limp.

Silence fell over the gym, broken only by the whimpering of the broken fighters on the floor and the humming of the fluorescent lights overhead.

I slowly turned my head toward the octagon.

Dustin was backed up against the chain-link fence inside the cage. The smug, arrogant boy who had sneered at me five minutes ago was gone. In his place was a terrified twenty-four-year-old realizing he was locked inside a building with a predator he couldn't comprehend.

I picked up a roll of heavy athletic tape from the counter, walked slowly toward the cage, and stepped through the door.