Five years ago, undefeated underground biochemical fighting league "Pantheon" champion Marcus Cole nearly killed his opponent with his own hands before retiring from the ring, swearing never to fight again. Five years later, pharma giant Victor Solari kidnapped Marcus's sister Lily—because her blood was the "universal donor" for manufacturing all god-tier serums. To save his sister, Marcus returned to Pantheon in pure flesh, fighting superhuman monsters injected with gene serums. Every battle was a flesh-versus-steel underdog comeback. But as Marcus fought deeper, he uncovered a more terrifying truth: a "silent gene" slept dormant inside him—the original template for all serums. Victor didn't want him to win; he wanted Marcus's genes fully activated through combat. Marcus had to choose between the fatal temptation of activating the gene and keeping his humanity, while bringing his sister alive out of the depths of hell.