Ho-jung, who enjoyed the prime of his fighting career with the title of an indomitable champion, hits rock bottom in life due to a sudden shoulder injury that led to retirement and an addiction to gambling. With debts amounting to 700 million won, his wife, who had been barely managing to pay off the interest, runs away with their son. At the moment when debt collectors were about to take away his organs, Ho-jung encounters a mysterious man. The man proposes whether he is willing to participate in the underground's biggest fighting arena, 'Brutal Cup.' Without realizing the implications for his future, Ho-jung readily accepts the offer from the man...