Bellamy freaks out that he has been locked in the bunker and doesn't know what his sister's fate was. Clarke is convinced that Octavia did not win the conclave. She allows Abby and Bellamy to radio Kane and Octavia.
Octavia reveals that she won the conclave and promised the bunker to all the clans, to be shared equally with 100 survivors from each of the clans. She tells Bellamy that she is managing to hold the grounders off from discovering that Skaikru stole the bunker, but can't for much longer. Bellamy promises to fix it but is incapacitated and taken into custody by the guards.
Clarke feels increasingly guilty about having ordered the bunker sealed shut, knowing now that Octavia won and managed to unify the clans. She confides in Niylah. Bellamy, in custody, injures himself trying to escape his restraints and save his sister. Clarke and Jaha put Murphy on Bellamy watch, knowing that Murphy will not allow Bellamy to open the bunker door and compromise his safety. Abby visits to help tend Bellamy's wounds and ends up teaming up with him to open the bunker door because she wants to save Kane too.
Abby and Bellamy manage to incapacitate Jaha and open the door. As Bellamy prepares to unseal the bunker, Clarke holds him at gunpoint to try and stop him. She threatens to kill him, saying that this is the only way to ensure that humanity survives. Bellamy talks her down and she doesn't shoot him. Bellamy opens the door and he and Octavia have a joyous reunion. Octavia turns on Echo, banning her from taking refuge in the bunker because of her treachery during the conclave.
Inside the bunker, the other clans have all chosen their 100 survivors. Now, it is time for Skaikru to do the same, choosing 100 of their own who get to survive in the bunker. Octavia mandates that Bellamy is one of the 100.
Raven works on building her spacesuit so she can go to space and spacewalk once more before dying. She is assisted by her hallucination of Becca. She begins hallucinating Sinclair, who convinces her not to give up fighting to stay alive. He walks her through the process of "rebooting" her brain in order to remove Becca's code (which is killing her) from it.
Raven successfully manages to stop her heart for 15 minutes and restart it (avoiding brain damage by lowering her body temperature). She radios back to the bunker to let everyone know that she is coming.
Back at Arkadia, the increasing levels of radiation are beginning to make everyone sick. Monty starts wearing a hazmat suit and tries to convince everyone to come with him back to the bunker -- they have enough room for him to ferry people back in the rover. Everyone refuses to go with him. Riley overdoses on the drugs that everyone has been taking, dying peacefully.
Jasper decides that they will all do this, so they can die before the radiation poisoning gets to them. Monty attempts to convince Harper to come back to the bunker with him, but she tells him she doesn't love him and won't stay alive for him. Jasper kills himself, but Monty finds him and (after failing to convince Jasper to live) has a chance to tell him he loves him and say goodbye.
Monty finds the bodies of all the other who stayed behind in Arkadia -- except for Harper, who had a change of heart and agrees to go back to the bunker with him.