Snowpiercer, Volume 3: Terminus

On a future, frozen Earth, humanity has been packed onto self-sustaining trains, doomed to circumnavigate the globe until the end of the interminable ice age - or until the engines give out. When a scrap of music piques their interest, the inhabitants of the Icebreaker take the ultimate risk and cross the frozen ocean, a vast expanse with no train tracks...and no way to return to them.