The prison

de Sŏng-un Yi, Hyun Na

"An action drama about violence and machinations within a Korean maximum security penitentiary. After a fatal accident, former police inspector Yu-gon is sentenced to hard time in a prison filled with those he helped put away. Once inside, he discovers the entire facility is no longer controlled by the guards but by a vicious crime syndicate headed by Ik-ho that breaks out at night, using their prison sentences as the perfect alibi to commit complex heists. Looking for revenge against the system that placed him inside, Yu-gon joins the syndicate, but with every man for himself, the alliance is shaky at best." -- Amazon.