'Jung-man', tired of his daily life, comes up with an idea of 'human sandbag' as part-time to make money. From that day on, the tough guy, 'Hwi', and the strongest guy 'Mingyu' teamed up on the road with only one glove in hand. However, escape is quick, neither money nor instinct make them satisfied, and the blood-boiling fighters' thirst is only getting deeper. One day, a mysterious alumni, 'Yoo-young' appeared and made an extraordinary offer to triple their profits, and they secretly got themselves in running a gambling den. The dumb-heads jumped into a fight in the gambling den instead of the streets. The moment the betting begins, there is no turning back!

Sang-gu, a notorious teenage street fighter, gets tired of fighting when he realizes there’s no match for him anymore. However, one day, his best friend Moon-je gets beaten up by Min-gook, the champion of mixed martial arts tournament in his school. Outraged by what happened, he decides to transfer to Min-gook’s school for revenge and enters the tournament. As he beats other opponents one by one, he gets closer to the big shot of the school, Min-gook.

Back at home, Chuck relates the island shenanigans of his larva pals Red and Yellow to a skeptical reporter in this movie sequel to the hit cartoon.