Jaha, Murphy and the rest of the crew searching for the City of Light are on a boat. They are tired and frustrated, but are revived when they see land. In the excitement an oar falls overboard. When reaching over to grab it, one of the crew falls in. Before they can pull him out he is attacked by a frightening shark-like creature.
The animal gets one more, and Jaha hold Murphy back from helping to save his life. Murphy doesn't quite agree with Jaha's logic to let him die so they could live.
In the Reaper tunnels, Octavia finds Fox dead. She reunites with Clarke, but is not happy to see her. Bellamy also joins them and they share a much happier reunion. Jasper and Monty are happy to see Clarke and Octavia, as well.
The reunion is cut short because Maya is running low on oxygen. They split up. Octavia goes with Jasper and Maya to level 5, while Bellamy, Clarke and Monty head out to get help from Dante.
Meanwhile, Lincoln is being restrained. He is still upset that Lexa broke the alliance and left the Sky People to be slaughtered. Indra believes in obeying her commander, but gives Lincoln the ability to make his own choice. She leaves him a knife so that he can join the Sky People if he decides that is where his loyalty lies.
At Mount Weather, Cage is accumulating prisoners. Raven and Wick are chained up alongside Miller, Harper and others. Hooded prisoners are brought in and revealed to be Kane, Abby, Miller's dad and Monroe.
Raven is chosen to be next up for bone marrow withdrawal. She fights back, but is subdued and restrained before drilling begins.
Former President Wallace won't help the Arkers. He believes that he doesn't have a choice, since the mountain needs either Grounders or Arkers to survive. He is not happy with what he has to do, but will bear it for the good of his people.
They take him at gunpoint to the command center.
Jaha and Murphy make it to land. Murphy is hurt, but still not happy with Jaha's methods. He tells him he is going his own way. Jaha believes that he had to sacrifice the few for the many. Jaha leaves Murphy to follow another drone.
Once at the command center, they are able to see the footage from the Mountain surveillance cameras. They see the prisoners and Raven. Clarke uses a walkie to contact Cage.
Clarke tells Cage she will kill his father if her people are not released. Dante tells Cage not to accept the deal and Cage listens, knowing that he can't save his father and the rest of the Mountain Men. Clarke has to follow through so that Cage knows that she is serious, so she shoots Dante in the chest, killing him.
Jasper, Maya and Octavia make it to level 5, and Octavia agrees to help Jasper kill Cage.
Meanwhile, Cage takes Raven off the table and goes for Clarke's mother, Abby, as retribution. Clarke wants to eradiate level 5.
Jasper has his own plan and takes Octavia's knife to kill Cage. He tells Maya he loves her and leaves.
Murphy wakes up on beach and finds more solar panels. He also finds a swanky house and after exploring, finds the kitchen to get himself a snack and something to drink.
Two kids making out see Maya and Octavia. Octavia runs after them and kills two security guards in the process.
Octavia and Maya are caught on level 5, while Jasper is also caught and brought to Cage, although this is part of his plan to get close enough to kill him.
In the command center, Monty has succeeded in developing a way to let outside air into the level, which would eradiate the floor and cause everyone to die. All it will take is one pull of a lever.
Clarke and Bellamy are torn on what they should do, but when Bellamy sees that Octavia has been captured he becomes certain.
He tells Clarke they will pull the level together.
Jasper runs to Maya, who dies in his arms.
As they are releasing the prisoners, Clarke, Bellamy and Monty are faced with the dining hall massacre. Bodies are draped over the table and a lone soccer ball alludes to the children who were clearly part of the fallen.
Jasper can't believe that they did this when he only needed a little more time to kill Cage.
Abby and Clarke are reunited, as are the Millers. Kane gives Bellamy a pat on the back.
Outside the mountain, Lincoln attacks Cage in woods. Cage tries to use a tone generator to disable him, but Lincoln cuts his hand off. In a fitting ending, Lincoln injects Cage with the Reaper drug and leaves him in the woods.
As the Arkers return to Camp Jaha, Clarke stands on the periphery. She tells Bellamy she can't go in and is leaving. He asks her to stay and grants her forgiveness, but she leaves anyway.
Murphy is getting comfortable in the City of Light. He is watching a video of the past where a man is talking about a woman who is to blame for something. At the end of the video he shoots himself.
Jaha finds the house where the drones are originating. He is greeted by a woman, who tells him that she has been waiting for him. She is a hologram and the episode ends with her thanking him for the inactive nuclear missile that he used to get to Earth, which she now has in her possession.