Picking up where the season one finale ended, Clarke is still alone in the white room, frantically trying to make sense of her bizarre surroundings, while the fate of Bellamy, Finn and Raven is still unknown. Lincoln and Octavia's daring plan is thwarted and an enemy returns. Meanwhile, Abby, Kane and the survivors of the Ark must face physical and moral dilemmas in their dangerous and beautiful new world. Finally, Jaha makes a heroic decision.
A suspicious Clarke confronts President Dante Wallace and demands answers. Kane interrogates one of The 100, and Abby performs emergency surgery. Meanwhile, Octavia resorts to violence to find Lincoln.
When Clarke discovers a horrifying project being carried out in Mount Weather's medical ward, she joins forces with an unlikely ally. After Abby confesses to committing a crime, Kane issues an order to have her brutally punished. Meanwhile, Monty warns a distracted Jasper that Clarke could be in trouble, and Octavia continues to fight for Lincoln.
After being betrayed by someone she thought she could trust, Clarke takes matters into her own hands and proves she's not going down without a flight. Bellamy, Finn and Murphy race against time to save a stranger. Meanwhile, tensions rise between Raven and Wick while working together, and an unexpected reunion occurs.
Kane leads a mission to make peace with the Grounders. Meanwhile, Jasper agrees to participate in a risky experiment, Lincoln enters a world of pain and President Dante Wallace issues a warning. Finally, Finn's search for Clarke takes a violent turn.
Tensions run high between Clarke and Finn, while Raven discovers that Mount Weather is interfering with their communication systems. Meanwhile, Jasper and Monty discover the truth about what's going on at Mount Weather and Octavia comes face-to-face with her worst nightmare. Finally, President Dante Wallace is about to be betrayed by those closest to him.
Abby is determined to find a way to protect her people from a coming attack by the Grounders, even if it means heading into unknown territory and leaving some captives behind. A worried Bellamy convinces Clarke to go with him to the drop ship, where he and Octavia reveal a dangerous secret. Clarke comes up with a bold new plan to stop the Grounders' attack, leading Abby to a desperate decision. Meanwhile, at Mount Weather, Jasper and Monty begin to question the motives of their new friends, while Dr. Tsing conducts a deadly experiment to determine how to make use of the captives.
Clarke returns to Camp Jaha with devastating news. Finn struggles with the aftermath of his actions. Abby gathers information from an unlikely source and prepares for a fight. Meanwhile, flashbacks reveal Finn and Raven's relationship on the Ark.
Clarke strikes a deal with Lexa and Indra. Abby and Kane begin to realize that decision making powers are out of their hands. A seething Raven is unable to control her emotions. A bold move threatens to destroy the newly formed alliance between the sky people and the Grounders, and a familiar face haunts Clarke. Meanwhile, back at Mount Weather, Monty comes up with a risky plan.
Lives are at risk as Clarke and Lexa encounter a new enemy. Bellamy and Lincoln agree to work together to break into Mount Weather. Murphy helps Jaha confront his past. Meanwhile, Indra makes Octavia an offer she can't refuse.
Bellamy and Lincoln's attempt to sneak into Mount Weather has brutal consequences. Abby fights to stay in control as Clarke steps up in her new leadership role. Meanwhile, with Monty and Harper still missing, a desperate Jasper confronts President Wallace and demands answers.
Tensions between Clarke and Abby come to a head after Clarke crosses the line. Raven helps Bellamy navigate Mount Weather. Jaha and Murphy encounter a stranger who may not be what she seems. Octavia is prepared to fight for someone she loves. Meanwhile, things reach a breaking point at Mount Weather.
Clarke begins to question Lexa's leadership decisions. Abby struggles to help an injured Kane. Indra continues to push Octavia. Meanwhile, at Mount Weather, Jasper steps up into the role of leader, and Cage throws Maya into a life threatening situation.
While preparing for battle, Clarke and Lexa have a heated discussion. Desperate for help, Raven has Wick summoned to the engineering room. Jaha and Murphy encounter a perilous roadblock. Meanwhile, at Mount Weather, Bellamy is in a race against time.
Clarke and Lexa prepare for battle, while Raven and Wick experience a major setback. Meanwhile, Octavia and Lincoln are each forced to make a difficult decision. At Mount Weather, Jasper and Maya witness a horrible act, Bellamy follows through on a promise and Cage goes public with powerful information.
The journey to the City of Light continues, and Jaha makes a move that shocks Murphy. Clarke receives help from an unexpected source, a visitor surprises Octavia, and Lincoln gets his revenge. Meanwhile, at Mount Weather, Cage moves forward with his mission and Bellamy and the group struggle to break free.