The fists of Taekwondo boys explode on a remote uninhabited island...!! The Taekwondo demonstration team for children who came to the beach for training are caught by gangsters who travel between the beach and the island and are sold to the island. The children who woke up on the island began to live a hellish life, where they are beaten severely even for small mistakes, and even adults had to work hard and live like slaves . On the other hand, Yong-Pal, who has lost the children, searches for the children with the police, but their whereabouts becomes obscure. Then by chance he finds out that gangsters using begging children and he gives chace.

Seung-hyeon, a construction team leader with PTSD, is ordered to inspect Dohak Station, where a fatal accident halted work years ago. Inside the eerie, abandoned tunnels, he and Joo-young encounter two mysterious workers and become lost while trying to escape. Meanwhile, a CEO and a shaman perform a ritual to resume construction, but enraged spirits retaliate, plunging everyone into chaos.