The story of Double Dragon is set in a post-apocalyptic version of New York City, five years after a Nuclear War, where gangs and criminal organizations take control of the city. The protagonists are Billy and Jimmy Lee, the titular duo and the successors of a fictional martial arts style known as Sou-Setsu-Ken. One day, Billy's girlfriend, a former student named Marian, is kidnapped off the street and the Lee brothers receive a letter from her captors, the Black Warriors, demanding to known the secrets of the Double Dragons in exchange for her release. The Black Warriors are the largest criminal organization in the city.