Season 1

Complete listed story — includes the ending

1. Pilot

Set in an indeterminate year in the future, 97 years after a nuclear apocalypse has devastated the surface of Earth, all known humans are residents of merged orbiting space stations known as the "Ark". 100 juvenile delinquents are sent to Earth's surface to test its habitability, having been given vitals-monitoring wristbands and instructions to proceed directly to Mount Weather. Among them is 17-year-old Clarke Griffin ( Eliza Taylor ), the daughter of the Ark's chief medical officer, Dr. Abby Griffin ( Paige Turco ). The 100 discover a lush Earth filled with new wonders and dangers. Clarke and four others search for the former Mount Weather Emergency Operations Center, a possible site of supplies. Ultimately, they discover that there are hostile survivors on the ground when Jasper, one of their party, is speared. The other delinquents remain at the landing site and, under the leadership of Bellamy ( Bob Morley ), celebrate their new world. Back on the Ark, Chancellor Jaha ( Isaiah Washington ) has been shot, causing the merciless and unsympathetic Councilman Kane ( Henry Ian Cusick ) to take charge. After Abby uses too many supplies to save Jaha, Kane attempts to execute her but, Jaha recovers in time to issue Abby a pardon.

2. Earth Skills

Chancellor Jaha recovers and learns of his son Wells' supposed fate on the ground. Abby recruits Raven, a zero-gravity mechanic, to fix a drop pod to send herself to the ground. On Earth, Clarke, Wells, Murphy, and Bellamy set out to rescue Jasper, who was taken by the grounders after being attacked. They find Jasper tied to a tree and manage to return to camp with him, in addition to a panther they killed prior his rescue. Bellamy forces the 100 to trade their wristbands for food. Clarke and Finn manage to keep them. As the Ark watches more wristbands going offline believing they are dying, a figure watches the 100 from above the camp.

3. Earth Kills

In flashbacks, Clarke's engineer father Jake discovers a life support problem with the Ark, is arrested for threatening to tell the people and " floated " by Jaha. In the present, Clarke, Finn, and Wells search for antibiotic seaweed to treat Jasper's infected wounds. Bellamy assembles a hunting group who are followed by Charlotte, a troubled 13-year-old whose parents were executed by Jaha. A lethal acidic fog hits, forcing Clarke, Finn, and Wells to seek shelter. The three talk, and Clarke berates Wells for his apparent part in her father's execution believing he told his father of Clarke's father's intent to commit treason. Bellamy and Charlotte take refuge from the fog; he comforts her when she has a nightmare. One of the 100 is fatally burned by the fog, forcing Clarke to mercy kill him; she subsequently succeeds in saving Jasper. Clarke discovers her mother's culpability in her father's death, learning that she actually told Thelonious, knowing her father would be floated. Clarke and Wells reconcile. Later, Charlotte's misinterpretation of Bellamy's advice leads her to kill Wells.

4. Murphy's Law

Monty attempts to use the wristbands to contact the Ark. Octavia and Jasper discover Murphy's knife outside the wall with two fingers, which are Wells'. Clarke publicly accuses Murphy, inciting a mob that begins hanging him. Overwhelmed, Charlotte confesses and Murphy is cut down. Charlotte flees camp with Clarke and Finn, and they take refuge in a bunker, pursued by a revenge-seeking Murphy. Feeling guilty, Charlotte attempts to turn herself in, but Bellamy intercepts her. The whole group ends up at a dead-end cliff where Charlotte jumps off and commits suicide, and Bellamy banishes Murphy; the incident brings the formerly feuding Clarke and Bellamy together as a strong leadership front for the 100. Monty accidentally fries all of the wristbands. Finn runs to the bunker in frustration, Clarke follows, and they have sex. On the Ark, Abby and Raven go to great lengths to acquire a pressure regulator, but Kane finds out and has Abby arrested. Raven launches off the Ark alone and prepares to enter the atmosphere.

5. Twilight's Last Gleaming

Raven, unconscious, has made it to the ground. Bellamy reaches her pod first and throws away her radio as he was the one to shoot Jaha and fears repercussions from his actions. Clarke and Finn follow, and help Raven, who is revealed to be Finn's girlfriend, leaving Clarke devastated. They catch up with Bellamy and tell him of the 300 people to be culled from the Ark to preserve oxygen. He helps locate the radio, but it cannot be repaired in time, so they devise a plan to fire "flare" rockets that the Ark will see, confirming that Earth is survivable. On the Ark, the approved plan calls for sealing off and deoxygenating Section 17. A desperate Abby reveals her husband's discovery to the Ark, causing some residents to volunteer for the culling. After the culling, Abby, imprisoned, and Jaha watch in surprise as the "flare" rockets appear in the viewport above Abby's cell. Octavia is captured by a grounder.

6. His Sister's Keeper

This episode's plot summary may be too long or excessively detailed. Please help improve it by removing unnecessary details and making it more concise. ( September 2020 ) ( Learn how and when to remove this message ) In flashbacks, Bellamy witnesses Octavia's birth. Due to the Ark's one child rule, Octavia is forced to live beneath the floor of her family's quarters. When Octavia is 16, Bellamy takes her to a masked ball for Unity Day. She is caught, and their mother is floated. A year later, Commander Shumway convinces Bellamy to assassinate Jaha in exchange for a place on the dropship with his sister. In the present, Bellamy assembles a search party for Octavia, and they leave for the woods. The group is ambushed by grounders, resulting in three deaths before they are suddenly called off by a foghorn. Clarke and Raven travel to Finn's bunker in hopes of finding a radio transmitter with which to contact the Ark, and Raven discovers Finn's involvement with Clarke. Bellamy, Finn, and Jasper rescue Octavia who has been protected by the grounder who captured her. Finn discovers that the grounder was the one who called off the attack. Seconds after that the grounder stabs him. Jasper hits the grounder unconscious. As a storm approaches, Clarke warns that she can only save Finn with her mother's help and they must repair the radio.

7. Contents Under Pressure

In the midst of a hurricane on the ground, Finn is near death from a poisoned stab wound. Bellamy, having captured the grounder who stabbed Finn, tortures him for the antidote but he does not speak. Raven successfully connects with the Ark; Abby assists Clarke with treating Finn. Octavia convinces the grounder to reveal the antidote by poisoning herself with the same blade. On the Ark, Abby is released due to the unexpected support of Kane, but is removed from the Council as punishment for her actions. Replacing her is the former chancellor, Diana Sydney, whose intentions are questionable. After learning that Earth is habitable, the Ark begins preparations for Project Exodus: their re-colonization of Earth. However, their dropships can only carry about 25% of the Ark's population. In addition, residual tension from the culling causes mistrust in the Council. Clarke finally confronts her mother who insists that she only intended to have Jaha talk Clarke's father out of his plan, not execute him.

8. Day Trip

Video connection is established with the Ark. the Ark informs the 100 of a nearby underground depot that may serve as a winter home. Bellamy and Clarke investigate and discover a stockpile of weapons and supplies. Dax, whom Commander Shumway is coercing to kill Bellamy, follows them. Octavia takes advantage of the camp's suffering from the effects of hallucinogenic nuts gathered as rations and frees the grounder, whose name is Lincoln. Bellamy, also hallucinating, is wracked with guilt for the culling and almost killed by Dax; Bellamy manages to kill Dax with Clarke's help. Clarke appeals to Jaha to pardon Bellamy for his crime using his actions on the ground; Jaha agrees in exchange for the name of the person who hired Bellamy. This leads to the arrest and imprisonment of Shumway. He is visited by Diana Sydney, and it is revealed that Jaha's assassination was her idea. Diana then has Shumway killed in his cell and framed to look like a suicide.

9. Unity Day

"Unity Day" arrives, when the joining of the orbiting space stations is celebrated. As the 100 celebrate, they find their video link interrupted when a bomb explodes during the ceremony on the Ark. Diana engineers a mutiny in order to hijack the first dropship. As the ship launches, it is not fully disconnected from the Ark's main systems, causing an Ark-wide power outage and disabling every dropship. On the ground, in an effort to initiate peace, Finn arranges a meeting with the local grounder leader through Lincoln. Clarke represents the group and goes to the meeting, where she meets Anya, a grounder leader. Anya reveals that the 100's "flares" burned down a grounder village, causing the grounders to desire their destruction despite it having been an accident. Jasper, who along with Bellamy is monitoring the meeting from cover, believes he sees the grounder spotters in the trees about to shoot, he opens fire, and the meeting dissolves into battle. That night, Clarke and Bellamy see the dropship descending. It comes in too fast with no parachute and violently crashes in the distance.

10. I Am Become Death

The 100 discover no survivors at the Exodus dropship. Murphy returns to the dropship after being captured and tortured by the grounders for information about the group. Shortly afterwards, a viral hemorrhagic fever spreads through the camp and Clarke realizes the grounders used Murphy as a form of biological warfare. Bellamy, Raven and Clarke all contract the disease though Octavia and Finn are immune. Octavia learns from Lincoln that this is his people's way of softening the battlefield and that the virus will soon pass; Lincoln intends to flee the area and warns of Mountain Men who will be after them. Raven builds a bomb to delay the coming attack, but collapses from the virus before it can be detonated; Finn rescues Raven while Jasper detonates the bomb just in time with Monty's help. Later, Murphy smothers Connor as revenge for his part in Murphy's hanging. Raven breaks up with Finn after realizing that he's in love with Clarke. At least three of the 100 die of the virus, but the rest begin to recover.

11. The Calm

Monty discovers a strange signal on the Exodus dropship's black box that apparently caused it to crash. After a fire destroys most of the food supply, the group sends out hunting parties to restock. Clarke, Finn, and Myles go out together, but Clarke and Finn are captured and brought to the grounder camp. Anya instructs Clarke to save Tris, her second, a young girl who was injured in the bomb blast. Clarke tries to save her but is unsuccessful. In revenge, Finn is taken away to be executed. Clarke escapes by killing her guard and runs. Bellamy, Raven, Octavia, and Monty search for the missing party and find Myles, hurt in the woods. Monty mysteriously disappears after hearing a strange signal on their hand radios. Kane awakens on a devastated Ark. He searches for survivors and saves engineer Wick, then he realizes Jaha is alive in the Earth Monitoring Station and trying to bring systems online. With over half the Ark's populace likely dead, they discover that there are survivors in an access bay to the exodus ship. With Wick's help, Kane braves the extreme heat in a maintenance tunnel to reach the survivors—including Abby.

12. We Are Grounders - Part I

Clarke is recaptured by Anya, and they encounter a grounder named Tristan, who assumes command. Clarke is saved by Lincoln and taken to a very much alive Finn. Lincoln leads the two through a network of tunnels occupied by the reapers, cannibalistic humanoids the grounders themselves are afraid of. Lincoln seemingly sacrifices himself so Clarke and Finn can live to warn the others, including Octavia. Back at the dropship, Murphy has taken Jasper hostage. Bellamy trades himself for Jasper. While Raven attempts to open the dropship door, Murphy shoots his gun aimlessly at the floor after hearing a gasp, accidentally shooting her. Murphy prepares to hang Bellamy. She finally succeeds in opening the door only to find Bellamy dangling, but is able to rescue him. Murphy retreats to the upper level, Murphy blows a hole in the ship with gunpowder and escapes with a radio. A returned Clarke convinces the group to flee the camp for the ocean where they'll be safe. On the Ark, with the dropships no longer functional, Jaha realizes that the only way to save the rest of the citizens is by bringing the Ark and its people to the ground.

13. We Are Grounders - Part II

The 100 are ambushed by grounder scouts and forced to retreat to camp. The remaining citizens of the Ark prepare to return to Earth. After a technical failure to jettison requires manual intervention, Jaha remains on the Ark to an inevitable suffocation in one to two weeks when air runs out. Mecha Station, with Abby and Kane, makes it to the ground. Back at the dropship, Tristan leads the grounders' attack. The 100 mount their defense. Octavia is injured and leaves with Lincoln. Most of the 100 retreat into the dropship; Anya leaps in after them and is subdued. As previously planned, Jasper manages to activate the dropship's rockets; the massive fireball kills all 300 of the grounders, and apparently Finn and Bellamy. When the 100 emerge from the dropship, gas grenades drop at their feet, and they all pass out. Clarke wakes up in a white room. Through the window in her door she sees Monty locked in an identical room across the hallway. A sign next to his door reads "Mount Weather Quarantine Ward".