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.

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.

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

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.

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.

Layton and Till investigate the murders. Wilford leads Miss Audrey down a dark path.

An engineering catastrophe on Snowpiercer forces Layton to make a difficult choice, one that might cost him everything.

Wilford presses forward on his endgame while those who are close with Layton grow anxious to learn their fates; Josie tests her newfound ability.

As the train approaches Melanie's retrieval point, Layton leads a furious attempt to try and pick her up but not without some sacrifices.

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

It's a game of cat and mouse as both Layton and Wilford vie for the upper hand.