In the immediate aftermath of Arkadia's destruction, a mob finds and attacks Ilian, brutally beating him. Kane stops everyone, intervening and shooting a gun into the air.
Clarke, Roan, and Bellamy set off with a few of Roan's men to deliver the last remaining barrels of hydrazine to Raven at Becca's lab. En route, the group encounters Trikru. The clans are warring, after half of the Azgeda army deserted en route back to Polis and began burning Trikru villages to the ground. Clarke gets out of the truck to help the wounded, but is unable to do anything. When Trikru realizes that Roan is in the truck, they attack, but the group narrowly escapes with the barrels intact.
They arrive at a river that wasn't there days earlier. Roan and Bellamy go to find a way to cross, while Clarke stays behind with the hydrazine and Roan's men. When Bellamy and Roan find a way to cross, they radio Clarke but she doesn't answer.
They go back and find one of Roan's guards dead, with Clarke and the hydrazine missing. Looking for her, they find Trikru (who they assume took Clarke and the truck) and fight them off, but Roan realizes that it wasn't Trikru but his own men who took the truck.
They find Clarke, and Roan manages to jump onto the truck to fight off the traitor from his group, killing him. Bellamy manages to shoot the Ice Nation warrior holding a knife to Clarke's group. All seems to have been saved, but when the trio gets to Becca's lab, they realize a Trikru arrow pierced one of the barrels and it drained completely.
Meanwhile, back at Arkadia, tensions rise as the Sky People rile themselves up over Ilian having destroyed their one definite shot at safety. Monty attempts to convince Jaha to intervene, but Jaha is getting drunk with Jasper instead.
Octavia, completely hardened and still angry at Bellamy for Lincoln's death, eventually assists the mob in getting in to attack Ilian, but insists on being the one to kill him herself. Kane tries to hold off the mob, but David Miller incapacitates him in order to allow the others to take Ilian. Outside, she essentially moves to reenact Pike's execution of Lincoln.
Kane manages to talk her down from killing Ilian, after he and Jaha falsely sound the black rain alarm in order to get the mob to scatter. Octavia runs off, leaving Arkadia behind, and Jaha releases Ilian, who does the same.
At Becca's lab, Raven pushes herself to her limits, running the rocket simulation, trying to figure out a way to safely land the rocket on the minimal fuel they have left. Murphy "babysits" her. After failing the simulation 29 times in a row, Raven has a breakdown and attacks Murphy, ruthlessly tearing him down verbally as well.
Luna intervenes, calming Raven down. Luna later convinces Murphy to help Raven. The three brainstorm and come up with the idea for Raven to crash land the rocket in the water. When Raven tries that in the simulation, it works, and she's elated. However, that elation proves shortlived.
When she exits the simulation, Murphy and Luna break the news that Clarke arrived with the hydrazine, but one of the barrels was drained. Raven breaks down, having a seizure. Luna tries to help her, as Murphy runs to get Abby.