Comics' Greatest World: X #1

Professional hitman Gamble accepts the contract from corrupt developers the Llewellyn brothers to kill Arcadia's self-appointed vigilante X, but X gets to the brothers first. Gamble is picked up by Arcadia mob boss Carmine Tango and told to continue his contract against X. X nearly defeats Gamble on a tenement rooftop until Gamble sets off a bomb that makes the building a burning inferno. X lets Gamble go in order to save a street kid who lives in the building.