Ruth takes Asha into Ag-Sec to see if she’d like to work in there. Asha takes to it.

Flashback to Ruth reaching out to her in her quarters, confronting her about stealing and hoarding. Asha confesses to what she did in the reactor. Ruth tells her that there is redemption to be found on the train.

Oz comes by and gets some hot spices for pickling. Asha makes chai for the other Ag-Sec workers.

Layton considers his options while watching over Liana.

Asha serves the chai and Layton walks into Ag-Sec.

Layton and Asha discuss his “vision” and she confirms the calendar image is what he saw. Ruth comes to find Layton to take him to the engine.

Ben and Alex tell them Melanie may be alive. Something on the tracks is moving.The thought is that Melanie got down from the climate station along the test track and got herself into a maintenance machine. It’s unlikely she’s stayed alive all these months with no support, so it may be just her body in an autonomous machine. To intercept the vehicle, they’d need to take a two-day detour. Alex also discloses that the information comes from Wilford.

Layton checks in with Wilford.

The train makes the detour. Alex and Ben discuss the possibility of Melanie being dead.

Asha’s trying to relax in her quarters when an alarm sounds in her equipment from the reactor.

Layton and Zarah spell things out for their relationship. Asha knocks on their door, dressed in her reactor suit. She tells them her equipment has detected an increase in sulfur dioxide. As she tries to show the science to Alex and Ben, Layton notices the horizon is distinctly discolored.

Asha’s readings show the composition will burn a person’s lungs out. Alex reads it as going for a couple hundred kilometers.

LJ finds Oz dancing with his pickles in the Night Car and is angry that he’s excited about getting off the train. She’s upset about the news that Melanie’s alive, calling her her arch-enemy. She wants to know where Wilford’s people are and what the real plan is.

Audrey catches Bess in the Market to ask about Melanie.

Layton returns to Wilford’s car and brings him to the engine to see the poisonous gasses ahead on the track.

In theory, the air scrubbers should keep the toxicity down to a breathable level and the design of the train should be able to withstand the corrosiveness of the hydrogen sulfide. The passengers are all told to return to their quarters to shelter in place until the emergency has passed.

Till invites Audrey to shelter with her in her quarters.

LJ makes her way to the Headwood lab and insists on coming in. When she insists that she can be useful to Wilford’s cause, Dr. Headwood asks her blood type as a test. The real test is having LJ donate a slab of skin.

In one of the Ag-Sec cars, the poisonous gasses are getting in, killing the plants.

Sykes helps Javi face his fear of Jupiter.

Audrey and Till get to her quarters. Till checks in with the Engine who tell her she can shelter until the danger has passed.

Sykes and Javi are checking the cars for air toxicity.

Ruth and Asha share a drink while sheltering in hospitality. They talk about how they traveled before The Freeze.

Once the readings come back normal, Ben and Alex send Wilford back to his cell car. Roche checks in with Carly. They discuss how to deal with Anne’s absence and dance to some smooth rock together.

Zarah and Layton check-in with each other.

In Till’s quarters, Bess is drinking heavily while Audrey abstains. Eventually, Till asks her Audrey to help her heal.

Zarah brings Liana to see Wilford.

Sykes and Javi find the car where the scrubbers aren’t working.

Ben and Alex realize the air intakes aren’t sealing. Ben sends Layton get a breach suit on. Layton tells them to send Asha to him.

Sykes starts to pass out from the fumes. Javi has a panic attack but forces himself past it to save her.

The fumes are spreading throughout Ag-Sec. In order to get to the jammed air intake seal, Layton plans to remove his breach suit because he can’t fit through the vent with it on. Ben advises against it strongly. Asha knock Layton down and does it herself. After the vents are sealed, she isn’t able to climb back out. As she’s dying, she asks Layton to describe New Eden to her.

LJ gets dressed after making her skin contribution to Dr. Headwood’s lab. As she’s being rushed out the door, she hears a voice moaning. Dr. Headwood escorts her out and rushes up to her inner lab to check on a patient.

The train emerges from the gas bank. Ruth checks in on Layton. Asha had told him to keep going for New Eden. Ruth supports this plan.

Till and Audrey lie on Till’s bed, facing each other. Till feels better. The shelter in place order is lifted. Both women close their eyes and rest, holding hands.

In the Engine, Alex and Ben sight the moving maintenance vehicle that may be carrying Melanie.