In Becca's lab, Abby and Jackson discuss how they'll use Luna's nightblood to reverse engineer it if they can't find out how to make it from the records Becca left behind. While they're talking, Raven suffers a seizure, having an out-of-body experience of herself floating over Abby and Jackson before they intervene and save her.
Octavia rides her horse back towards Arkadia but collapses before she can get there. Ilian comes upon her and brings her back to Arkadia. Her heart stops beating, but Clarke manages to save her. Octavia, near unconscious, warns Clarke that Azgeda is coming. Clarke and the others formulate a defense plan. Monty reports back that Kane isn't answering his radio, while Bellamy and Stephens are nowhere to be found.
Niylah is also at Arkadia, having been recruited to dry the meats that the Sky People hunters have been getting. Clarke doesn't tell her about the radiation, but reminds her to charge the radio she gave her.
Roan rides with his army towards Arkadia, and Clarke goes to intercept them. Roan isn't inclined to chat and orders his archers to aim at Clarke. The hidden Skaikru train their own guns on Roan, getting him to cease fire. Roan brings out Bellamy and Kane, tied up, in order to get Clarke to call her guns off. He agrees to a few minute conversation with her privately in a cave, to Echo's trepidation.
Riley refuses to stop targeting Roan to take him out, not believing the Ice Nation can be reasoned with. Monty talks him down. Meanwhile, Bellamy realizes that Octavia may actually be alive.
Inside Arkadia, Niylah takes care of a recovering Octavia. Octavia panics when she realizes Ilian is the one who brought her and that he's inside Arkadia. Ilian, meanwhile, loads up a cartful of explosives and walks around inside the station while everyone else is distracted.
Back at Becca's lab, Raven awakens after her seizure, having had an epiphany about how to recreate the nightblood -- her hallucination gave her the answer. She shows Abby and Jackson that the nightblood would bond with the RNA in a zero-G environment. She also uncovers that there is a rocket that can get them into space so they can make the nightblood there.
While everyone waits at attention as Roan and Clarke have their conversation, Monty notices that Riley has snuck off, taking his rifle while leaving his radio. Monty attempts to get into the cave to stop Riley from executing Roan and starting a war.
In the cave, Clarke questions what Roan is doing and what happened. Roan explains that they're not there to kill the Sky People; they're there to take Arkadia for their own. Clarke tries to explain the nightblood solution will save everyone, but Roan sees that as Skaikru making their own commander, also in violation of their agreement. Roan tells Clarke that the options are to fight it out or for Clarke to hand over Arkadia. Clarke offers to share the station.
Monty makes his way over to Echo and informs her, Kane, and Bellamy about Riley. Echo and Bellamy go together to the cave in order to stop Riley, while Kane and Monty remain behind as hostages in case Echo doesn't make it out alive.
In the lab, Jackson and Abby do a brain scan on Raven and realize that Raven is using a huge percentage of her brain -- and that she has evidence of a stroke. Abby tells Raven, who refuses to slow down and reveals that it must be that part of ALIE's code is still in her brain because she was pulled out of the City of Light using the EMP. Abby tries to tell Raven that going this hard could kill her, but Raven refuses, saying she needs to keep going to save everyone. Jackson voices concern that the EMP, also used on Abby, could have harmed her brain too. Abby declines using the brain scan on herself to check.
Roan and Clarke agree on splitting Arkadia, with 50 spots apiece, in order to avoid a blood bath. Echo and Bellamy find Riley, and Bellamy manages to talk him down successfully from killing the king.
Octavia tells Niylah that Ilian is going to try to destroy all tech and that he used her to get in to Arkadia. They run to the server room to find him about to destroy it all to avenge his family. Octavia tries to explain to Ilian that they need the ship to survive, but Ilian blows it up anyway. From a distance, just as they're discussing the plan to share Arkadia if the nightblood solution fails, Clarke, Bellamy, Roan, and Echo see Arkadia explode.
Everyone rushes back to Arkadia to see it destroyed as everyone who was inside rushes out. Bellamy takes care of Octavia as everyone watches Arkadia burn and collapse in horror.
Back at the lab, Abby hallucinates seeing a radiation deformed Clarke tell her that she's running out of time.