As an unidentified virus sweeps the country, the Korean government declares martial law. As the country descends into chaos, one city, Busan, is rumoured to have successfully fended off the virus outbreak and remains the only beacon of hope for those not yet infected. But when the virus breaks out on an express train to Busan, passengers on board must fight for their own survival. 453 km from Seoul to Busan. The struggle to survive. Get on board to stay alive.