Season 2

Complete listed story — includes the ending

1. The 48

Finding Monty gone from his cell, Clarke breaks out and discovers she is trapped in an underground complex inside Mount Weather. She discovers that an entire population of humans has survived but are unable to go outside because they have never built up resistance to radiation. After meeting their leader, Clarke and the 47 remaining members of the 100 are invited to stay in Mount Weather. Distrusting him, she makes a break for freedom but is stopped by Jasper; she proceeds to plot an escape. A vengeful Tristan hunts the few members of the 100 that avoided capture; Abby, Kane and the Ark survivors save them and kill Tristan. At the dropship, an injured and dying Raven kills a grounder survivor and is tended to by a remorseful Murphy who reveals his tragic background; they are later found by the Ark survivors and the kids they had rescued. The group returns to the newly established Camp Jaha. Separated from everyone else, Lincoln tries to save a poisoned Octavia, but with no antidote, he is forced to take her to his village, knowing it will mean certain death if he is caught.

2. Inclement Weather

Chancellor Jaha discovers a baby left on the Ark and plans to take him to Earth. While a suspicious Clarke confronts Dante, Octavia is healed by Nyko, a friend of Lincoln's. Octavia holds Nyko hostage and offers him to Indra, the village leader, to get Lincoln back. Abby performs surgery on Raven to remove the bullet from her spine without anaesthesia. Jaha learns that the baby is a hallucination of his son caused by oxygen deprivation, who convinces him to continue living his life; Jaha crash lands a nuclear missile carrying him to Earth. During the prisoner exchange, Octavia is attacked by the reapers, who capture Lincoln. Clarke learns that Anya — the leader of the grounders — is being held in Mount Weather with other prisoners being forced to supply blood to heal the mountain residents.

3. Reapercussions

Clarke and Anya escape Mount Weather into the reaper tunnels. Abby is punished for supplying guns to Finn. Bellamy and the others leave Camp Jaha to search for their friends. Octavia joins Indra's hunting party to follow the reapers and retrieve Lincoln but he is not among the grounders they intercept. In Mount Weather, Jasper and Monty worry about Clarke's whereabouts. Kane goes after Finn, Bellamy and the others and appoints Abby chancellor in his absence. Clarke and Anya risk their lives to escape the tunnels, then Anya takes Clarke hostage. Lincoln is shown to be in Mount Weather, and it is revealed that the reapers work with the mountain men, bringing prisoners to Mount Weather and being fed dead grounders.

4. Many Happy Returns

Chancellor Jaha is found in a desert and rescued by a boy named Zoran, living with his parents who left their people in search of a place in the "dead zone" called the "City of Light". Searching for their friends, Finn, Bellamy and the others find a survivor from the Ark — Mel — who is saved by Bellamy after Sterling dies while trying to rescue her. While Clarke and Anya are on the run from mountain men, Raven starts working in the camp again alongside Wick, who has made her a brace for her leg. Octavia finally reunites with Bellamy and the others. Chancellor Jaha is forced to leave Zoran and his parents when Zoran's father trades him for a horse. On their way out of the woods, Clarke and Anya arrive at Camp Jaha. At the end, Ark soldiers shoot and kill Anya and knock out Clarke, after mistaking her for a hostile grounder.

5. Human Trials

Clarke is brought into Camp Jaha and, after receiving medical attention from Abby, is reunited with Bellamy, Octavia, and Raven. They go after Finn and Murphy. Kane is hoping to find peace with the grounders but instead is imprisoned at the grounder camp, where he discovers Jaha is also a prisoner. Lincoln is being held at Mount Weather where he is the subject of experiments involving a red drug that turns grounders into reapers. Jasper takes extreme measures to save Maya from radiation exposure by allowing a blood transfusion conducted by Dr. Tsing. After Maya's successful treatment, Dr. Tsing and Cage – Dante's son and Lincoln's torturer – ask President Wallace for permission to move forward with trials on the 47. He refuses. Elsewhere, Finn holds an entire grounder village hostage while searching for Clarke. Clarke, Bellamy, and Octavia arrive in time to see Finn gun down 18 grounders.

6. Fog of War

Two days after the massacre, Raven discovers that Mount Weather has been jamming communications which caused the crash of the Exodus drop ship. Leaving camp to investigate, Bellamy and Octavia discover that Lincoln has become a reaper. Clarke still has not spoken to Finn. Raven manages to listen in on Mount Weather's radio broadcasts and discovers that the acid fog from before is a weapon of the mountain. In Mount Weather, Wallace wants Jasper to find volunteers to provide blood for the mountain residents but he fails. Maya discovers the radiation leak she was caught in was no accident and confides in Jasper about the mountain's caged grounders. In captivity, Jaha and Kane are told that one of them must kill the other to gain an audience with the Commander. Kane attempts to take his own life rather than kill Jaha but a grounder witness, named Lexa, reveals herself to be the Commander and says that she believes their wish for peace is sincere. She sends Jaha to Camp Jaha with a message; leave within two days, or die.

7. Long Into an Abyss

With the grounders' deadline imminent, Abby and Jaha disagree over what the survivors are to do; Jaha wishes to evacuate to the so called "City of Light", while Abby wants to remain behind to rescue the 47. Clarke, Octavia, and Bellamy hold the reaper-state Lincoln in the drop ship and learn he was drugged and experimented on. Lincoln's heart stops but is restarted by Clarke, who believes there is a way to cure reapers – information they can use with the grounders. When Abby cures Lincoln, Lexa grants Clarke the truce but demands Finn's execution for the massacre before it can begin. In Mount Weather, Jasper, Monty, Miller and Harper discover that there are Ark survivors on the ground. Dr. Tsing learns that for the mountain residents to live on the surface, they would have to kill the 47 for their bone marrow. Though Wallace vetoes the plan, his son Cage goes behind his back and begins the process with Harper.

8. Spacewalker

Clarke returns to camp with knowledge of the only way the grounders will accept a truce. Opinions are divided when Clarke reveals the grounders will cease their attack if they are given Finn. Flashbacks to the Ark reveal that Finn was imprisoned because he took the fall for Raven's illegal spacewalking. At Camp Jaha, Abby and a returned Kane think they can bargain with the grounders by offering to put Finn on trial, but such plans are for naught, as Finn ultimately turns himself in. In a last-ditch effort to save Finn, Clarke goes to meet with Lexa. When Lexa refuses clemency, Clarke asks to say goodbye. She approaches Finn, kisses him, and tells him that she loves him while stabbing him to death, saving him the brutal torture/execution of grounder custom.

9. Remember Me

Clarke and a group from the Ark accompany Finn's body to a grounder camp to complete their agreement for a truce. Clarke is haunted by visions of Finn. Bellamy fails to convince Clarke to let him go to Mount Weather as an inside man. At the village, Finn's corpse is burned along with those of the massacre victims. Kane gifts Lexa a bottle of liquor, which when tested appears poisoned, leading to the belief it was an assassination attempt by the Sky People. The grounders accuse and prepare to execute Raven but Clarke and Bellamy pinpoint Gustus, Lexa's right hand, as the culprit. Later, Clarke changes her mind and sends Bellamy, along with Lincoln, to infiltrate Mount Weather.

10. Survival of the Fittest

Clarke and Lexa encounter a gigantic mutated gorilla after one of the grounder council members drives Clarke into the forest with the intent to kill her. They escape it but become temporarily trapped in its cage and Lexa is injured. Clarke figures out a way to escape and has an idea about freeing the grounders inside Mount Weather to act as an insider army. Bellamy and Lincoln plan their infiltration of Mount Weather en route to the reaper tunnels but upon arrival Lincoln is overcome by his addiction, leaving Bellamy to a questionable fate. Murphy helps Jaha confront his past, while Jaha persuades Murphy that the Sky People have nothing to offer him and that his best option is to search for the mystical "City of Light". Jaha then leaves the camp with over a dozen Ark survivors, with Murphy tagging along, to search for the "City of Light". After witnessing Octavia's determination and unwavering spirit to fight, Indra offers to make Octavia her second in command but Kane warns Octavia that once the war ends it is likely that the grounders and Sky People will end up breaking their alliance.

11. Coup de Grâce

Bellamy is caged in Mount Weather along with numerous grounders. Jasper's search for Monty and Harper remains fruitless, so he confronts the President about their disappearance. Cage sends snipers to assassinate Clarke and Lexa; they are intercepted and one is captured for questioning. Maya discovers Bellamy being harvested for blood and saves him with help from an imprisoned grounder named Echo; he makes contact with Clarke. President Wallace and Jasper discover Dr. Tsing's illegal experiments on Harper and Monty. Cage ousts his father as President and orders a lockdown for the surviving 47 teens. Realizing she has to draw attention to the outside for Bellamy's sake, Clarke sends Emerson, their captive, back to Mount Weather with a message boasting about the army that is coming for them.

12. Rubicon

An unmasked Cage rescues Emerson on the surface, revealing the success of the bone marrow experiments. In the dormitory, Jasper tells the others of Bellamy's presence. Jaha, Murphy and his group encounter a strange woman, a scavenger and drifter named Emori, who offers to serve as guide to the City of Light through the "dead zone" desert. Emori is not who she appears to be. In Mount Weather, Bellamy seeks a way to help his friends; with the help of President Wallace, Bellamy irradiates several of the mountain men to death, including Dr. Tsing, allowing the 47 to escape. When Bellamy makes radio contact, Clarke and Raven overhear Cage's plan to bomb the planned peace conference in Tondc. Clarke races to the village, where she explains the danger to Lexa, who convinces Clarke that an evacuation would expose Bellamy's presence in the mountain; the two secretly escape. As they leave, Clarke sees her mother arrive in the village and returns to try to rescue Abby as the missile hits the village.

13. Resurrection

Clarke and Abby survive the missile strike on Tondc but Abby is horrified to realize that Clarke knew it was coming and did not evacuate the village. She goes back to help survivors, while Lexa and Clarke set off to find and kill the spotter who called in the strike and is still shooting. Lincoln saves Indra's life, while Octavia leads the other seconds in an effort to dig out survivors. Abby finds Kane pinned below rubble and struggles to free him, while they wonder whether they deserve to survive at all. Clarke finds and kills the spotter with Lincoln's help and realizes that the spotter's lack of a hazmat suit means the mountain men have started harvesting her friends. Inside Mount Weather, Jasper and the others fight back and find refuge with those in Mount Weather who do not agree with Cage.

14. Bodyguard of Lies

Lexa decides to kill Octavia to protect the secret that she and Clarke knew about the missile strike in advance. Clarke stops her and Lexa reveals that she has feelings for Clarke. Bellamy, Raven and Wick find a way to disable the acid fog; Bellamy soon discovers it was a trick but radio contact has been cut and he has no way to warn the others. Lexa agrees to trust Clarke and not hurt Octavia; Clarke notes there is more to life than survival. Lexa kisses Clarke who says that she isn't ready for a relationship. On Raven's signal that the fog is disabled, Clarke and Lexa lead the army to Mount Weather. Bellamy manages to destroy the acid fog system just as the mountain men are deploying it. Elsewhere, Jaha, Murphy, and crew continue to search for the City of Light. They take casualties crossing a minefield and reach a lake where a mysterious boat appears.

15. Blood Must Have Blood, Part One

Bellamy is letting the grounders imprisoned inside Mount Weather out of their cages as Cage starts to raid the complex for the 47. Some of them are temporarily captured but freed again by Bellamy, Jasper and Maya, who bring them to the harvest chamber. Soldiers soon raid the harvest chamber too, taking the 47 prisoner once again. Cage visits his father, desperately hoping he will tell him a way to stop the incoming attack. Raven and Wick destroy the mountain's generators and the lock on Mount Weather's door is disabled. When they pull the door open. Lexa commands her people to stand down – she has made a deal with Emerson, her people will be freed if the grounder army retreats leaving the Sky People left for dead. It is later learned that this was Dante's suggestion. When the grounders retreat, almost all the Sky People accept defeat and soon leave too, leaving behind only Clarke at the front door and Octavia in the tunnels.

16. Blood Must Have Blood, Part Two

Clarke joins Octavia in the tunnels and is let into Mount Weather by Bellamy. With the 47 waiting for bone marrow extraction, Clarke and Bellamy take Dante hostage. When Cage still refuses to stop, Clarke shoots his father, which leads Cage to begin bone marrow extraction on Abby. Seeing no other option, Clarke has Monty hack into Mount Weather's air filtration system and she and Bellamy irradiate the mountain, killing the entire population, including Maya. Cage escapes but comes upon Lincoln, who injects Cage with the reaper drug, killing him, leaving Emerson, who also escaped, as the last Mountain Man. Everyone returns to Camp Jaha but Clarke, wracked with guilt over the deaths of hundreds of people, leaves. Jaha and Murphy arrive at an island where they separate. Murphy finds a lighthouse inside of which he watches a video recording (dated May 10, 2052) of the previous occupant who says she "got the launch codes", before shooting himself. In the final scene, Jaha finds a well kept mansion, surrounded by flying drones, where he meets an A.I., named "A.L.I.E.", in the hologram form of an attractive dark-haired woman wearing a red dress, who thanks him for his "gift", the nuclear warhead from the missile he used to land on Earth.