In the midst of boxing's contemporary golden age -¬ the 1980's -¬ stood two fighters who established a captivating rivalry. Their pair of bouts within a span of just over 5 months in 1980 had all the trappings of instant classics. Sugar Ray Leonard, an American hero, who had become a household name after a Gold Medal-winning performance at the 1976 Summer Olympics that led to numerous corporate sponsorships, versus the Latino champion, Roberto Duran, the toughest -¬ some said meanest -¬ fighter of all time. It was not just the drama and action of these fights that would endure, but those two words uttered in the second of their clashes, which would create a sense of mystery, bewilderment and intrigue to the present day. No Mas unveils for the first time what really happened, going behind the scenes of these two showdowns with the help of boxing experts, family members and the two fighters themselves.