The Snowpiercer crew marvel as a rocket shoots through the sky, crashing nearby; Melanie sends Till and Ben to investigate; nine months later, New Eden blooms.
Milius and his Animal Squad storm the train; Melanie realizes something is wrong and shuts the vault doors to the engine; when Ben's life is threatened, Melanie surrenders the engine.
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.
Layton learns who was responsible for the experiments on Josie and Liana, before also finding out who froze the world; Big Alice approaches New Eden but can't cross the boobytrapped bridge.
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; Alex finds herself in danger.
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.
Nima heads for Snowpiercer; Layton and the Tailies fight their way uptrain when Ruth is captured; Nima tries to cut a deal and runs to the rocket control room to initiate the launch sequence.
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.
It's a game of cat and mouse as both Layton and Wilford vie for the upper hand.
Alex finally deals with her parental figures as a track obstruction uncovers a painful past.
A series of terrorist attacks threatens to derail Layton and Zarah's big day.
As the bomber is revealed, Layton comes to terms with his past decisions before making an irreversible call.
As the train grapples with Layton's status, he's discovering that some dreams aren't worth having; Wilford makes a shocking discovery.
As the train detours from New Eden, an environmental catastrophe threatens everyone onboard.
Reunited with old friends, the train throws a party; alliances are tested as the truth is finally revealed.
It all comes to a head as old adversaries clash, with New Eden hanging in the balance.
An exchange is made between the two trains, but a far greater revelation might be just over the horizon.
Melanie embarks on her most dangerous mission yet, while Layton reckons with his personal choices.
As the Big Alice crew is granted shore leave on Snowpiercer, Layton and Wilford have differing opinions on the future.
Layton and Miss Audrey make a risky play for Big Alice, but Wilford has his own plans.
Melanie fights for survival in treacherous conditions, vying to do what others before her could not.
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 goes forward with his endgame; Layton sinks to new lows.
As things hit their darkest point, Layton hatches a plan.
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.
Layton uses his new position as train detective to investigate the murder while gathering intelligence for the revolution on the side; Melanie faces a resource crisis, with potentially drastic consequences for the entire train.
Layton descends into Snowpiercer's 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 shocking twist in the murder investigation brings Layton and Till's manhunt to a cat-and-mouse climax; Layton gets closer to Melanie's big secret, which may prove the most dangerous game of all.
Hiding out with help from his allies, Layton lays track for revolution; an engineering emergency threatens every soul on Snowpiercer.
On a divided Snowpiercer, Melanie intensifies her search for Layton; Layton is weaponizing her secret; Third Class faces a reckoning when he presents them with a choice.
Revolution has finally come and Layton leads the lower classes forward in armed rebellion; Melanie's house of cards collapses and she's in danger of becoming the first casualty.
The rebel forces are on the ropes when a dangerous foe defects to their side; they hatch a final plan to take control of Snowpiercer once and for all, but it comes at a grave, moral cost.
In the revolution's aftermath, Layton struggles to govern the shell-shocked survivors; Melanie finally makes peace with her demons.