The fourth season of Snowpiercer picks up where the third season left off, with the train still hurtling through the frozen wasteland. The story takes place several months after the events of the previous season, with the survivors still reeling from the aftermath of the revolution. The season introduces new challenges and conflicts, as the passengers of Snowpiercer face a new threat: the arrival of a mysterious train, known as the "Big Eater," which seems to be on a mission to destroy Snowpiercer.