Still trapped in Clarke's room at Polis, Clarke and Murphy hear the horn signaling the start of the Conclave. Clarke tells Murphy that they need to make sure Aden wins and becomes the next Commander. After banging on the door, Titus opens it and gives Clarke and Murphy robes to sneak into the Conclave, fulfilling his vow to Lexa. Clarke demands to see Aden.
Titus reluctantly takes Clarke to see him. Aden is with the other Nitblidas, in a ceremony with Lexa's body. Clarke asks Aden whether he'll protect her people, as Lexa said. Aden explains that all of the Nightblood novitiates will protect the Sky People, if they are chosen. They all promised Lexa and all loved her.
Clarke is moved. They are interrupted by Roan and Ontari arriving. Ontari attacks Clarke but Roan pulls her off. Ontari vows that when she becomes Heda, Clarke and every last member of Skaikru will die.
Back at Arkadia, Lincoln counsels his fellow prisoners to stay strong. He tells Kane that he will not let Kane give up either. Pike and Bellamy arrive. Pike announces that each of the prisoners is guilty of the same crime as Kane, and they will each share the same punishment -- execution. Lincoln asks Pike not to punish his people. Bellamy backs Lincoln. Pike agrees to spare the Grounders but sentences Lincoln, Sinclair, and Kane, as the leaders of the coup, to be executed at dawn.
Bellamy and Monty secretly meet with Harper and Miller. Bellamy cuts out the listening device that Bryan planted on Miller and tells them that Pike sentenced Sinclair, Lincoln, and Kane to death. Bellamy and Monty offer to help them rescue the three from inside. Harper and Miller refuse to give up any information about a rescue plan because they don't trust them. Bellamy tells them to tell Octavia to meet him at the drop ship if she wants to save Lincoln.
Octavia meets Bellamy that night. She pretends to move to embrace him but injects him with something that knocks him out instead.
Clarke and Murphy go down to Titus' room. He tries to kick them out but Clarke demands to know why Ontari was allowed into the Conclave. Titus explains that because she has the blood of the Commander, she must be allowed to compete. He warns them that if Ontari is chosen, the Sky People will face her wrath. They hear the victory horn and rush upstairs to find Ontari, covered in blood and surrounded by the heads of the Nightblood children, sitting on the Commander's throne. Roan holds Clarke back, telling her if Ontari sees her, she'll have Clarke's head.
Bellamy wakes up chained in a cave. He offers to help Indra and Octavia rescue Lincoln, Sinclair, and Kane. They refuse his help, citing that the prisoners wouldn't need help if not for Bellamy.
Miller confesses to Bryan that he's a traitor, tricking Bryan into admitting he'd bugged him. Miller tells Bryan he can't have both Pike and Miller, making him choose a side.
Abby visits Kane and tries to tell him that she won't let the execution go through. Kane tells Abby not to do anything, because she will be executed as well. Abby starts to cry and tells Kane that she can't "do this" again. Kane leaves.
Roan escorts Murphy and Clarke to the tunnels, helping them to escape. Clarke wonders how he can support Ontari, a murderer of children. He tells Clarke that his debt to Lexa for sparing his life has been repaid, and that the next time they see one another, it won't be as friends. When Roan leaves, Clarke turns back around, telling Murphy that they are not leaving without the flame of the Commander.
Kane is accepting of death, explaining to the others that death can be an act of unity too. Pike and his men retrieve the prisoners. Harper radios to Octavia that they are on the move. Monty and his mother overhear and his mother realizes it is Octavia Blake with backup. She reports back to Pike what is happening. Pike has the prisoners moved into a secure room with guards while they investigate.
Bellamy, chained up outside the camp and watched over by Indra, tries to convince Indra to let him go, so that they can use Pike's trust of him against Pike. He warns her that Octavia doesn't know what she's getting into. Indra refuses to listen.
At Polis, Clarke and Murphy break into Titus' room so she can steal the flame chip. Titus finds her and stops her, telling her that she killed Lexa though he physically pulled the trigger. She tries to convince Titus not to put the chip in Ontari, but Titus explains that he must. Putting the chip in someone without Nightblood will kill them. Clarke is confused about the succession plan involving killing off those few with Nightblood, if it is so rare. Clarke brings up the eighth novitiate at Lexa's conclave, the one she didn't kill. Titus explains that the eighth novitiate fled and brought dishonor to the Commander line.
Ontari arrives, still covered in blood, and Titus hides Clarke. She demands that he put the flame in her. Titus tells her that she needs to be cleansed before she ascends. He instructs Murphy to go take her to perform the ritual. Murphy and Ontari leave. Clarke thanks Titus for turning against Ontari. Titus comments that perhaps even Luna would be a better choice than Ontari. Clarke recognizes the name as someone Lincoln has mentioned. Titus stays behind to deal with Ontari and getting Murphy out, instructing Clarke that she must perform the ritual on Luna when she finds her. He gives her the necessary tools to perform the ritual and the Commander's armor, and she leaves.
Pike realizes that the prisoners have apparently escaped, leaving the guards he left to watch them unconscious but alive. When he leaves, Octavia and the prisoners emerge from beneath the floor. Miller awakens Bryan, one of the guards who was willingly knocked out to make it appear that they'd escaped. Harper radios to warn them that the exit is not clear. Monty intervenes, radioing a false report that the prisoners are headed to the main gate. His mother is shocked that he is a traitor but doesn't give Monty up, only telling Pike they heard it was a false report.
Kane, Octavia, and the others escape. Abby chooses to remain behind, to help their people out of the darkness. Kane kisses Abby passionately, and she assures him they will meet again.
Pike makes an announcement over the speaker that if the escaped prisoners do not turn themselves in, the Grounder prisoners will be executed in their place. Lincoln opts to stay behind to save his people, kissing Octavia and injecting her to render her unconscious, knowing she wouldn't willingly allow him to remain behind alone. Kane carries her out and Lincoln is swarmed, held at gunpoint by Pike and his men.
Ontari bathes with Murphy in the room. Roan brings in Titus and explains that he doesn't have the chip. Ontari is angry and wants to kill Titus. They decide not to kill him when it's mentioned that he is the only person who can perform the ritual. Titus presses against Roan's blade, killing himself, saying "For Lexa." He bleeds to death in Ontari's purification bath. Ontari instructs Roan to light the pyre and burn Lexa, signaling that a new Commander has been chosen even though she doesn't have the chip. Roan is reluctant but agrees. Murphy volunteers not to tell anyone that she doesn't have the chip implanted, because he wants to keep his head.
Clarke rides off towards Arkadia, chip in hand, as Lexa's body is burned.
Indra hears the horn announcing the new Commander and realizes that Lexa has died. She rides off to return to her people at Polis, telling Bellamy to tell Octavia she is sorry.
Octavia comes to while the prisoners are riding off. She staggers back towards the camp. Pike prepares to execute Lincoln, promising that while he cannot release the Grounder prisoners, they will be cared for. Octavia witnesses Pike shoot Lincoln in the head, killing him.