Layton realises some dreams are out of reach. As the rest of the train deals with Layton’s status change, Wilford makes a staggering discovery.

Layton uses his new position as train detective to investigate the murder while gathering intel for the revolution on the side. Meanwhile, Melanie faces a resource crisis, with potentially drastic consequences for the entire train.

Layton descends into the black market with Till, searching for both the killer and a valuable commodity for his revolution. Melanie stages a prize fight to distract the passengers from mounting class tension.

A series of terrorist attacks threatens to derail Layton and Zarah's big day.

A shocking twist in the murder investigation brings Layton and Till's manhunt to a cat-and-mouse climax. But Layton is getting too close to Melanie's big secret, which may prove the most dangerous game of all.

On a divided Snowpiercer, Melanie intensifies her search for Layton while Layton is weaponizing her secret. Third Class faces a reckoning when he presents them with a choice.

Alex must finally deal with her parental figures as a track obstruction uncovers a painful past.

As the train detours from New Eden, an environmental catastrophe threatens everyone onboard.

A grisly murder stokes class division on Snowpiercer, the Great Ark Train. Melanie Cavill, the powerful head of hospitality, deputizes a dangerous rebel to help solve the killing -- Andre Layton, the world's only surviving homicide detective.

Hiding out with help from his allies, Layton lays track for revolution and an engineering emergency threatens every soul on Snowpiercer.

As the bomber is revealed, Layton comes to terms with his past decisions before making an irreversible call.

Layton demands to use Big Alice to rescue Liana. Ruth, now Mayor of New Eden, refuses because it's the town's power supply. Layton makes Javi jury-rig a solution, giving them three weeks of electricity.

Big Alice catches up to Snowpiercer. Milius radios them, inviting Layton over. Sensing a trap, Layton and Josie sneak onto Snowpiercer. Nima is worried Layton will be gassed and attempts to disarm the Greenhouse Car.

Nima needs more samples for his experiments, so Milius sends Wilford and the soldiers to collect. Privately, Milius tells Wolf to kill Wilford. Layton wakes up on an abandoned floor and is approached by humans with toxic gas scars.

Alex sabotages the track switch computer and, with Layton's help, escapes to town hall. Till gets the drop on Ace and uses his sniper rifle to save Layton and Alex from Rat. Melanie reveals the identity of Alex's biological father.

Tensions between Third Class and First Class are boiling as Melanie stages the trial of the Snowpiercer killer. Third Class threatens a work stoppage, demanding representation on the jury, and Melanie makes a fateful decision about which side to favor.

In the revolution's aftermath, Layton and Melanie realize the greatest threat to their survival is right over their shoulder.

Big Alice pulls into New Eden. Layton, Josie, and Liana sit stranded in the middle of nowhere, freezing to death, when a masked soldier appears. Can he rescue them? Alex finds herself in danger.

Revolution has finally come. As Layton leads the lower classes forward in armed rebellion, Melanie's house of cards collapses.

While Wilford emphasizes his rule aboard his icy train, Layton's pirate train continues its dangerous quest for warm spots, and comes across something entirely unexpected.

Layton learns who was responsible for the experiments on Josie and Liana, before also finding out who froze the world.

Layton goes on the hunt, as Wilford works to boost morale. The resistance discovers a threat that could undermine everything they've worked for.

The rebel forces are on their heels when a dangerous foe joins them. A plan is hatched to take the train, but it may destroy them all.

As the Big Alice crew are granted shore leave on Snowpiercer, Layton and Wilford have differing opinions on the future.

The Snowpiercer crew marvel as a rocket shoots through the sky, crashing nearby. Melanie sends Till and Ben to investigate. Flash forward to nine months later, New Eden blooms.