Dutiful soldier Callum Renwick wakes up in the underground laboratory of a mercenary organization. He learns he was the sole survivor of an attack that destroyed his unit, his hometown, and his family. In addition to the loss of his loved ones, he discovers that due to his injuries, half his body has been supplanted by artificial skin and cybernetic parts. Once he has recovered, he is assigned to the care of Ro Bernard, who leads the effort to turn him into a powerful assassin. She is outspoken, yet secretive, and uses unconventional means to mold him into a depraved killer. Mind games and rough sex are in her repertoire of training tactics, and Callum is both infuriated and fascinated by her. As he comes to terms with his grief and his new role, many of his biological body parts fail and must be replaced. Will he adapt to survive in Ro's world and exact vengeance on the woman who ordered the attack that changed his life?