No-holds-barred fighting is an extreme sport that combines elements of boxing, wrestling, and mixed martial arts and is so graphically violent that it was once banned in the U.S. Its premise is simple: one ring, two fighters, and no rules, resulting in one of the purest and most brutal forms of competition in all of sports. This graphic documentary takes an unflinching look at the world of no-holds-barred fighting and the modern-day gladiators who populate it through the eyes of Mark "The Smashing Machine" Kerr and his friend Mark "The Hammer" Coleman, two of the sport's most fearsome fighters. Director John Hyams follows Kerr and Coleman on their road to a championship tournament in Japan, documenting Kerr's struggles with drug addiction and Coleman's efforts to mount a comeback after humiliating defeat. The result is a powerful, harrowing, and realistic portrait of the all-too-human participants of a very often dehumanizing sport.