Thirteen

Thirteen is the seventh episode of the third season of The 100. It is the thirty-sixth episode of the series overall. It aired on March 3, 2016. It was written by Javier Grilo-Marxauch and directed by Dean White.

Summary
Lexa tries to maintain peace and order within the clans, and Clarke uncovers a strange and game-changing truth. Meanwhile, a flashback takes us into the darker chapter of humanity’s past.

Plot
Murphy is still imprisoned in an underground shrine, unconscious. Titus begins interrogating him again when Murphy comes to. He continues to ask about where he retrieved the City of Light Key, which is the sacred symbol of the Commander. Murphy explains to him that Jaha gave it to him, and explains its use. When Titus asks how this computer program ended the world, Murphy tells him that he does not have details, because on the Ark, they were told it was just countries and politics.

In a flashback, ninety-seven years ago, Becca and another scientist work on a larger, cruder version of the A.I. pill, with tentacle-like appendages, however it continuously malfunctions. Suddenly they get a transmission from Chris. He warns her that A.L.I.E. has gotten out and is on the grid. She is hacking nuclear launch codes. The woman asks why, and Becca answers with A.L.I.E.'s supposed problem with humanity: "Too many people."

Becca tells Chris to send out A.L.I.E.'s poisoned pill virus and kill her. Chris warns her that he has already done so and she has locked him out of everything. He is ordered to seek refuge in their lighthouse bunker. Polaris Commander, Cole, enters the lab and alerts them that twenty-seven ICBMs have been launched from China and are aimed for the United States.

From their space station, Polaris, they watch in horror as the missiles approach their destinations. Cole manages to contact his wife and daughter, but the signal is lost. The missiles from China make contact, and the United States fires back. The nukes drop on almost every major city, and the Earth is left simmering in radiation.

Back in 2150, Lexa and the Nightbloods celebrate Ascension Day. Suddenly, Semet barges into her throne room. He has Octavia prisoner, and claims that Skaikru has destroyed his village. He begs for his Commander to avenge them, and kill all of Skaikru. Clarke, Lexa, and Titus discuss the situation. Titus wants Lexa to destroy the thirteenth clan as a show of strength. While, Clarke wants to the Sky People overthrow Pike themselves.

At the end of the debate, Lexa decides to call upon the armies of the twelve clans and march on Arkadia, not to attack but to blockade them and allow Skaikru to take out their leaders from the inside. However, any Skaikru found past the five-mile buffer zone will be subject to a kill order. Semet attempts to assassinate her out of rage, but Titus executes him first. Once again, he tells Lexa that blood must have blood.

In the shrine, Murphy frees himself from his bonds and tries to escape. However, the door is locked. Preparing to defend himself, Murphy steals a spear from the pod, causing the door to close where it reads Polis, the name of the capital. He sees that there is a gap between the "Pol" and "is," which is singed away. Murphy, after analyzing the cave paintings on the walls, realizes that it once read Polaris.

In a flashback of 2054, two years after the world ended, Becca is seen injecting herself with a black fluid multiple times, altering her DNA and rendering her blood a black color. In her briefcase, it is seen that there are many more vials of the black fluid. Cole confronts Becca, having been told by her assistant that Becca's artificial intelligence program was what destroyed the human species. The commander is preparing to dock along with the other twelve stations, to create the Ark, and angrily tells her it is being designed to ride out the nightmare that Becca created.

They will not join the Ark, which is scheduled to unite in two hours, until the second A.I. is floated. Becca pleads that the A.L.I.E. 2.0 will save them on the Ark. She fears that the Ark will not survive with normal human scientists giving them calculations, and that the A.I. will help them survive because A.L.I.E. 2.0 will have a biologically-based human conscience and will know humanity's wants and needs because it will also want and need things that humans will. However, the Commander is not convinced and goes with Becca's assistant to find something to float the research in. Becca is still convinced that A.L.I.E. 2.0 will help them and locks herself in the lab.

Back in Polis, Clarke is faced with two choices: return with Octavia to stay imprisoned inside Arkadia until Pike is defeated, or remain in Polis with Lexa, who still has feelings for her. Titus is against the latter, and warns her that Clarke may become like Costia. This enrages Lexa, and reassures him that she is more than capable of separating feelings from duty. He apologizes, and she says that it is Clarke's decision on whether she wants to leave or stay.

Octavia finds Indra in the capital, and attempts to convince her to come back to help them battle the Arkadians. Indra feels as if her honor has been lost, and displays this when even Octavia proves to be superior to her in combat. However while Octavia waits impatiently for Clarke to join her, Indra appears and they head back to Trikru without Clarke.

Titus returns to the shrine where Murphy is waiting to attack. Titus defeats Murphy and nearly kills him until Murphy begins to explain what the shrine actually is. He tells him about the end of the world, the nuclear radiation, and why Skaikru needed to stay in space. Murphy explains that Polaris was the thirteenth station and that the woman in the cave paintings must have escaped and landed on Earth, and was just like the 100. Titus, while doubtful, says that Becca is nothing like Skaikru and knocks him out.

In another flashback, Cole warns Becca that the other stations are threatening to stop docking maneuvers because Polaris has not started. Alpha Station contacts Polaris and threatens to martyr them. Becca launches from the pod, wearing the commander's spacesuit. Alpha destroys Polaris to send a message to the other stations and forces them to join, threatening that the same thing will happen to the other federation stations if they choose not to join.

Clarke, who has decided to leave, says goodbye to Lexa. She hopes that one day, they will owe nothing more to each other's people and will be able to live peacefully. Lexa hopes they will meet again. Before she leaves, Clarke and Lexa have sex. Afterward, Clarke examines a tattoo on Lexa's back. She explains that she got it on her Ascension Day, and each circle represents each Nightbleeder who died. There were nine participants in Lexa's conclave, but only seven circles on her back. Clarke asks what happened to Number Eight, but Lexa says she does not want to talk about it, and they begin to kiss again.

As Clarke prepares to leave with Octavia, she finds Murphy outside Lexa's sleeping quarters. He is tied up and injured, but alive. Titus pulls out a gun, saying if he kills Clarke with a Skaikru weapon, she will think it was Murphy and may be so heartbroken that she will declare war and kill the Arkadians. Clarke manages to dodge the bullets, but Titus, who is not skilled with firearms, accidentally fires a stray bullet, which hits Lexa in the stomach.

Titus realizes what he has done and helps Clarke put Lexa on the bed so she can save her. She begins losing too much blood, but Lexa tries to calm Clarke and tells her not to be afraid. Titus prepares to retrieve her spirit and begs for forgiveness. Lexa simply haves him swear that Titus will never attempt to harm Clarke again, which he swears. She then tells him to do his job and serve the next commander as he served her. Clarke tries desperately to save her. Lexa is convinced that her spirit will find a new Nightbleeder, but Clarke only wants Lexa, and not another commander.

Lexa tells Titus that she is ready, and tells Clarke that her fight is over. She also manages to tell Clarke that life is about more than just surviving. Clarke then recites the Arkadian prayer to her, and kisses Lexa for the last time. Lexa dies shortly after. After convincing an incredibly saddened Clarke that he must complete the ritual. He turns Lexa over on her back, where above her Ascension Day tattoo, across the nape of her neck, is the same infinity symbol that Titus was interrogating Murphy about, and the same symbol on Jaha's pills.

Vertically down the center is a scar, which Titus reopens. As blood pours out, A.L.I.E. 2.0, now sentient, emerges. Titus puts it into the sleep mode, and stores it away in an old tin box. He carries away Lexa's body and alerts the Grounders that the conclave must begin and that Lexa is dead. Her spirit (the A.I. plucked from her nape) will choose the next commander. They lock Clarke and Murphy inside her chamber, and Murphy attempts to break free while Clarke stares at the black blood stains on the bed in shock.

Becca survives and lands on Earth, in the ruins of Baltimore during the nuclear winter. Her suit is breached and the radiation levels spike. The black fluid injected is presumed to counteract the effects of nuclear radiation as she was able to take off her helmet and breathe safely. Out of the debris Becca sees humans approaching in the distance, wearing hazmat suits. She tells them that she is here to help. It is implied that she would inject these survivors with the black fluid and make them immune to the radiation as well. It is seen that on Becca's nape, crudely stitched, is the same vertical cut that must contain the same A.I.

Starring

 * Eliza Taylor as Clarke Griffin
 * Bob Morley as Bellamy Blake (credit only)
 * Marie Avgeropoulos as Octavia Blake
 * Christopher Larkin as Monty Green (credit only)
 * Devon Bostick as Jasper Jordan (credit only)
 * Paige Turco as Abigail Griffin (credit only)
 * Henry Ian Cusick as Marcus Kane (credit only)
 * Isaiah Washington as Thelonious Jaha (credit only)
 * Lindsey Morgan as Raven Reyes (credit only)
 * Ricky Whittle as Lincoln (credit only)
 * Richard Harmon as John Murphy

Guest Starring

 * Alycia Debnam-Carey as Lexa
 * Erica Cerra as Becca
 * Adina Porter as Indra
 * Neil Sandilands as Titus
 * James Neate as Chris
 * Zak Santiago as Semet
 * Cory Gruter-Andrew as Aden
 * Roger Cross as Cole

Quotes

 * Lexa (to Titus): "I am more than capable of separating feelings from duty!"


 * Clarke: "I'm sorry."
 * Lexa: "Don't be. You have to go back to your people. That's why I.... That's why you're you."
 * Clarke: "Maybe someday, you and I will owe nothing more to our people."
 * Lexa: "I hope so. May we meet again."


 * Lexa: "My fight is over."
 * Clarke: "No, I won't accept that."
 * Lexa: "You were right, Clarke. Life is about more than just surviving."


 * Titus: "Forgive me, Heda."
 * Lexa: "You will never again attempt to harm Clarke. Swear it."
 * Titus: "I swear it."
 * Lexa: "Then do your job. Serve the next as you have served me, Flamekeeper."


 * Indra: "You see? Even someone as slow and as weak as you can put me on my back. I should have died on that field."
 * Octavia: "We all die. You can either do that here, feeling sorry for yourself, or you come back with me and get your revenge. The choice it yours."


 * Titus: "Love is weakness. To be Commander is to be alone."
 * Lexa: "I don't want to hear this again."
 * Titus: "Yes, you will. Your feelings for Clarke put both of you in danger. Your kill order must be fully enforced. If you care about Clarke, you will send her home and it is the only way she will be safe. Don't make her pay the price for your mistakes as Costia did."


 * Clarke (to Lexa): "In peace may you leave the shore. In love may you find the next. Safe passage on your travels until our final journey on the ground. May we meet again."


 * Lexa: "We gather here on this Ascension Day to honor the Commanders that came before me. Those who live on within me. As I will live on within one of you."


 * Murphy (to Titus): "She's a computer program. But I get that's hard for you to grasp, considering you pray to garbage. No offence....obviously."


 * Titus: "Your fight is over, Lexa of Trikru. The commander's fight goes on."

Notes and Trivia

 * This episode has the most amount of main cast missing from the episode, with only 3 appearing.

Body Count

 * Semet
 * Lexa
 * Most of the human population (Flashback)
 * Cole and the other crew of Polaris (Flashback)