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.