In the near future, South Korea enacts a law to specially detain juvenile offenders with a high recidivism rate, requiring them to obtain rehabilitation certification before they can return to society. This leads to the creation of a maritime juvenile prison, known as the "Prison Ship," where six young offenders nearing release are selected for a trial operation. However, due to a mysterious incident that causes a system malfunction on the prison ship, all inmates escape from their cells, initiating a survival game to escape from the prison ship.