Set in a post-apocalyptic New York, Double Dragon is the story of Billy and Jimmy Lee, twin brothers trained in the fighting style of Sou-Setsu-Ken. Together, they manage a small martial arts training school, teaching their students in self-defense. One day, Billy's girlfriend, Marian, is kidnapped off the street by the "Black Warriors", a savage street gang led by a man named Willy. The Black Warriors demand the Lee brothers disclose their martial arts secrets in exchange for Marian's freedom. The Lee brothers set out on a rescue mission to crush the Black Warriors and save Marian.
The gameplay of Double Dragon involves using various techniques such as punches, kicks, invulnerable elbow strikes, and any available weapons to pursue the gang through different environments like city slums, industrial areas, and forests until reaching their hideout. The ultimate goal is to confront and defeat the main antagonist, Willy.
The NES version of this game also includes an additional VS. fighting mode for one or two players. In this mode, players choose from a range of characters, including Billy and five enemy characters, and engage in a one-on-one fighting match where they must punch, kick, jumpkick, and use weapons until their opponent's health bar is depleted. The last player standing wins.