The game's main character is a man named Hayden Tenno, a morally ambivalent clean-up man employed by the CIA. He suffers from a real-life disease called congenital analgia that does not allow him to feel pain. On a mission in a fictional former eastern bloc nation, he is exposed to a biological compound which mutates him, dramatically changing his right arm, and giving him the ability to spontaneously grow a three-bladed throwable weapon called a glaive.