Zack Overkill and his twin brother Xander were super-powered mercenaries. They committed crimes for the money, not concerning themselves with any innocent deaths. When Xander was killed, Zack testified against his boss and entered the Witness Protection plan. As part of his parole, Zack must take drugs that suppresses his super powers. Working as a mail clerk in an office, Zack is bored out of his mind.