Bellamy makes his way into the Harvest Chamber in Mount Weather. He keeps his promise to Echo and frees her from her cage. They start to free the other Grounders and Bellamy tells Echo to help him get them ready to fight. The Grounders start to get excited and Echo tells them to be quiet. Bellamy starts to tell her the plan when Cage Wallace comes over the PA, announcing to all of Mount Weather that they can all return to the ground. He tells them that before the Delinquents murdered her, Dr. Tsing had found a cure in their bone marrow. Bellamy tells Echo he has to go save the Delinquents and that he's going to bring them back to the Harvest Chamber. Echo thanks him for his help. Cage continues talking over the PA, asking for the residents of Mount Weather to turn over the "44 murderers" and if they don't, they will be considered enemies. After Cage hangs up the PA, Emerson tells him that there is nothing they can do about the Grounder army marching on them from outside because their Veil is down and the army is too close for missiles. Cage tells Emerson that as long as they are behind the doors, the Grounders can't touch them. He then gets upset that Emerson hasn't found Bellamy, the intruder, yet and throws some papers around, telling Emerson to go door-to-door to find them.
Elsewhere in Mount Weather, there is a knocking at the door of Mr. and Mrs. Peters who are currently hiding Jasper and Maya Vie. Paul Tilling and another Mount Weather Guard enter and begin looking around and questioning them about the missing Delinquents. Mrs. Peters sets down her tea cup and Tilling notices two extra cup rings on the table. He pulls out his gun and shoves Mr. Peters onto the couch next to Mrs. Peters. He tells them they have five seconds to cooperate and begins counting down. Jasper breaks free from his hiding spot in a hole behind a painting on the wall and begs Tilling not to shoot them. Tilling puts a bullet into Mr. and Mrs. Peters' foreheads as the other guard handcuffs Maya and Jasper.
Clarke and Lexa are in their Command Post tent with their military leaders when Monroe and Sgt. Miller arrive and Sgt. Miller gives her a package of hydrazine from Raven. Abby isn't there because she stayed behind to help the wounded from the bombing in Tondc. Lexa and Clarke then begin to discuss the action plan and Clarke makes it clear that it is supposed to be a rescue mission and that they don't want to wipe out the Mountain Men. Clarke explains how there are four teams: one at the dam (Raven and Wick), one in the mines (Indra and Octavia), one inside the mountain (Bellamy and the Grounders), and Clarke's team who will take the front door. Clarke has found out from Maya that the main door has a flaw if the power goes out. Raven and Wick will take out the power coming from the dam, causing a one-minute delay before the backup generator kicks in. This gives them one minute to blow the lock on the door. The reason they don't also want to blow the backup generator is because it would leave the Mountain Men without power for too long, killing them all. Clarke then admits that they had lost contact with Bellamy after he blew up the Acid Fog machine. She goes on to tell them that once they get the door open, they will be under heavy fire from Mount Weather and that is what they want. While they are distracting the Mount Weather Guards, Indra and Octavia will be getting the Grounders and Delinquents out the back door and through the Reaper tunnels. Lexa then gives an encouraging speech, ending in the chant of Jus drein, jus daun ("Blood must have blood") and all of the Grounders chant after her.
Tilling and the other guard have now also captured Fox and Nathan Miller in addition to Jasper and Maya. They are stopped by Vincent Vie who begs Tilling to let his daughter go. Tilling tells Vincent to step aside and raises his gun at him. As Tilling steps closer to take the shot, he is suddenly shot in the head from the right side. Tilling falls as Vincent runs over to the air vent and pries it open, revealing Bellamy, while Miller takes down the other guard and bashes his head against the wall. Bellamy tells them to go with Vincent to the Harvest Chamber where they'll be safe. Jasper and Maya decide to go with Bellamy to rescue Monty and the other Delinquents. Maya gives a hug to her father in goodbye.
In the Reaper tunnels, Octavia is following a map Lincoln drew and tells Indra that he should be there to show them the way. Indra tells her that Lincoln wasn't ready yet. Octavia tells Indra it meant a lot that she forgave Lincoln and Indra says that he deserved it. Reapers arrive and some of the Ark Guards start shooting. Octavia and Indra both tell them to stop because the Reapers are not the enemy. As the Reapers attack, Jackson plays the tone generator and the Reapers fall down. They then inject the Reapers with sedatives and tie them up. Indra pauses, recognizing one of the Reapers.
At the front door, Monroe drills a hole into it so Sgt. Miller can insert the hydrazine bomb to blow the lock. Lincoln follows him to provide protection in case any of the Mountain Men try taking any shots. Sgt. Miller's hands start to shake as he tries to insert the bomb and Lincoln tells him to do it for his son. Sgt. Miller replies that the Mountain has taken enough from both of them and steadily inserts the bomb.
Meanwhile, Raven and Wick are setting bombs on the turbines of the dam. They have completed three with two more to go. Raven tries to lighten the mood with some jokes but Wick is being moody because she pushed him away after they had sex. They hear a voice come across a radio in the room asking for, "402: please report," when Wick is suddenly tackled by a Mountain Man trying to get to the radio. Wick beats him over the head with a metal tool and kills the man. Wick stares in shock as the radio voice tells 402 that backup is on its way. Raven tells Wick they need to hurry. They realize that in the scuffle, the last bomb dropped and broke, meaning they can only blow 4 of the 5 turbines and the power won't shut off.
Cage brings a tray of food to Dante's prison cell. Cage tells him the Grounders are going after their power at the dam and an army is outside the main door which they are drilling into. He tells Dante that he underestimated their Commander and Dante tells him succinctly that he underestimated Clarke. Dante tells Cage that in one week, Cage has turned the Mount Weather residents against each other, lost their outer defenses, and the door that withstood 97 years is going to fall with the Grounders coming in to kill them all. Cage asks Dante for help on how to stop it because they will destroy everything. Dante tells him that Cage already has. As Cage is about to leave, Dante stops him.
Raven and Wick are bickering about having lost the last bomb and how they should have brought an extra one when it makes Raven consider the redundancy of the turbines. If they blow 4 of the 5 turbines, the fifth one will keep running but at a lower capacity to keep it from taking the full load of the other 4 missing turbines. All she needs to do is make it take the full capacity of the other 4, causing it to overload into "catastrophic failure."
Clarke and Lexa wait for the power to go out and Lexa invites Clarke to their Capitol, Polis, telling her it will make her change the way she thinks about the Grounders. Clarke tells Lexa that she already has. They soon hear gunfire coming from the dam and get ready to blow the door.
Raven tells Wick to hurry and Wick finishes the last bomb, telling Raven to push the button. Their plan seems to work but they're interrupted by Mountain Men who tell them to put their hands up. Raven and Wick realize they are too close to the turbine and start to back away with their hands up. The last turbine explodes.
In Mount Weather, the power goes out all over the place and Cage tells Emerson over radio to start the clock for one minute. Emerson tells Cage he is not letting them get near the door. When the light over the door goes off, Sgt. Miller tells Clarke they have one minute to blow the lock. Clarke and Lexa hold the trigger and press the button together but nothing happens. Clarke realizes that Mount Weather is jamming the trigger signal and says she has to get closer. As she starts to approach the door, gunfire rains down from above and Lincoln grabs her to safety. Emerson and his men shoot at them from the ridge above the door, preventing them from getting close to the door. A group of Grounders create a moving shield to take Sgt. Miller to the door so he can trigger it manually. They are all shot down before they can make it. They only have a few seconds left when Lincoln comes up with the idea to use a flaming arrow to trigger the bomb on the door. He makes the shot with only a second to spare and the lock is blown. Lexa tells Lincoln to remain with Clarke while she takes a group up the ridge to take down Emerson's contingent so they can work on getting the door open.
In Mount Weather, Bellamy pushes his way out of an air duct as they look for the last 12 Delinquents. An announcement is heard, telling all Mount Weather residents that they have 30 minutes to get to Level 5 for quarantine lock-down. Maya realizes she is in trouble because she can't go to Level 5 without being shot. They hear a gunshot and rush toward it, waiting until the Guards are gone. They find Mrs. Ryan, the woman who was hiding the last twelve, dead. Jasper wants to go to Level 5 but Bellamy doesn't think that's a good idea. Monty comes out and tells them he hid and had to let them kill Mrs. Ryan because he overheard that the Mountain Men know about Echo's Grounder army and are going for the Harvest Chamber.
In the Reaper mines, they've reached the intake door to Mount Weather and Indra tells Octavia that she did well and that she is a Grounder now, much to Octavia's pleasure.
At the main door, the shooting has stopped. Monroe notices that Sgt. Miller is still alive underneath the Grounder shields and helps him. Lincoln then commands the other Grounders to start hooking lines onto the door so they can pull it open. As the door creaks open, Clarke gives the command to attack just as Lexa interrupts and tells them all to stand down. Lexa arrives from the ridge, towing Emerson along just as through the open door, harvested Grounders start stumbling out. Clarke asks if that means they surrendered and Emerson says, "not quite." Clarke asks Lexa what she did and Lexa tells her she saved her own people but Clarke's people weren't part of the deal. Emerson then heads back inside Mount Weather as Echo and the last of the Grounders are released. Lincoln asks Clarke what is going on and Clarke tells him what Lexa did. Lexa tells Lincoln the deal is done and orders the retreat to be sounded. Lincoln refuses to retreat and Lexa has him restrained. She then turns to Clarke and says, "may we meet again," before leaving with her army.
Down in the mines, Indra hears the horn sounding retreat and commands everyone to go. Octavia refuses because she doesn't trust Lexa and Indra tells her it is an order. Octavia refuses, telling her she is not leaving without her brother. Indra tells her she is no longer her Second and symbolically cuts her. After Indra and the Grounders leave, Jackson asks Octavia to come home with the Sky People. Octavia tells him she has no home and Jackson leaves a bag behind before taking off with the others while Octavia stands alone in the mines.
In Mount Weather, Bellamy, Maya, Jasper, and Monty have reached the Harvest Chamber. Maya discovers her dad, shot dead in the middle of the floor while Bellamy discovers every single one of the cages empty and all of the Grounders gone.
At the dam, Raven and Wick awaken after getting knocked out by the explosion. Raven's leg brace is broken so she can't walk without help. Wick tells Raven he won't leave her just as Mountain Men come in and take them captive.
Cage visits Dante in his prison again. He tells him Lexa took the deal and they won. Dante tells him they haven't won yet because the Sky People will never stop. Cage tells him he has already spotted a group headed their way and sent out some guards to pick them up for more bone marrow. He tells Dante they will be on Level 5 until the turbines are fixed and leaves the door unlocked.
Sgt. Miller, Monroe, and the rest of the Sky People tell Clarke it is time to go back to Camp Jaha to get reinforcements but Clarke refuses to leave, saying, "it can't be over," as she stands alone in front of the main door.