100 young exiles from a dying space station are sent to the planet Earth 97 years after a nuclear apocalypse to see if it's habitable.

After discovering that Jasper may still be alive, Clarke, Bellamy, Octavia, Finn and Monty set out to locate him and are shocked at what they find.

Clarke, Finn and Wells set out in search of an antibiotic to treat Jasper's wounds, when an acid fog forces them to seek shelter...and forgiveness for past crimes.

Abby risks having herself floated in order to give Raven the chance to stow-away in the escape pod bound for Earth.

After exposing Kane's plan to reduce the population of the Ark, Abby and Chancellor Jaha notice a signal from Earth and realize at least some of the 100 must still be alive.

While Bellamy leads his crew into Grounder territory in a search for Olivia, Raven can't help but notice the deep connection between Finn and Clarke.

While Clarke and Raven make contact with the Ark, Abby is removed from the council and Jaha reveals that there are not enough drop ships for everyone on the Ark.

While some of the 100 accidentally eat hallucinogenic nuts, Clarke and Bellamy go on a mission to find supplies for winter and are brought closer by a terrifying event.

All hell breaks loose when Clarke and Finn attempt to broker peace with the Grounders. And tragedy strikes during the Unity Day celebration on the Ark.

Murphy returns to camp claiming to have been held captive and tortured by the Grounders, and Clarke and Bellamy have very different opinions on how to handle his return.

With a low food supply at camp, Clarke and Finn lead a group out to hunt for food and wind up with Finn's life in danger. Meanwhile, Raven makes Bellamy an offer he can't refuse.

Those remaining on the Ark must come to terms with the inevitable. Meanwhile, Clarke and Finn find themselves facing a new enemy.

It's the end of the world as the conflict on the ground comes to a head and the situation on the Ark comes to a stunning conclusion.

Clarke struggles to survive on a desolate, scorched earth, while her friends in space come across a long-awaited beacon of hope.

Octavia is forced to take guidance from an unlikely ally when the future of the bunker and all those inside it is jeopardized.

Bellamy leads the charge investigating a potential way home. Meanwhile, Clarke and Madi deal with the new uncertain threat to their home.

Our heroes are forced to rely on the help of Shallow Valley's dangerous new inhabitants in order to save some of their own with surprising results.

Octavia leads her people toward Shallow Valley against the advice of Clarke & Bellamy. Meanwhile Kane and Abby adjust to a new set of challenges.

Kane's attempt to prove himself useful tests Wonkru's allegiance to Octavia. Madi faces an unexpected threat inside Wonkru, forcing Clarke to make an unlikely ally.

Clarke and Bellamy make a startling discovery about Wonkru's battle plans as Echo risks her friendship with Raven to complete her mission.

Clarke's determination to protect Madi puts Bellamy in an impossible situation.

The growing fractures in Wonkru threaten to explode once and for all. Meanwhile, in Shadow Valley, Murphy starts a fire, unleashing catastrophic results.

Monty strives to show Wonkru an alternative to war, and to the Valley itself. Meanwhile, Abby's health continues to deteriorate, along with McCreary's patience.

As Clarke races to save Abby, she learns more about the trials and tribulations Wonkru faced in the bunker, and the impossible decisions they were forced to make in the dark year.

Octavia leads her people into war. While behind enemy lines, our heroes must overcome their differences to save Wonkru from extinction.

Clarke and her friends must risk everything to fight one last battle for survival only to glimpse an even darker threat to the last living valley on Earth.

A small group goes down to explore the mysterious new planet, while members of Wonkru on the Mothership face the consequences of their decisions.

The team on the ground fights to survive the threat they face on the new planet. Meanwhile Raven must join forces with an unlikely ally to save everyone on board the Mothership.

Clarke tries to win over the leaders of Sanctum to let her people stay. Meanwhile, Bellamy, Echo & Octavia discover a new threat while on a mission to retrieve the transport ship.

Clarke embraces the traditions of Sanctum and tries to make amends for her past actions.

While Jordan investigates Sanctum, and Bellamy and Clarke butt heads, Octavia and Diyoza discover the threats of the new planet firsthand.

Diyoza learns more about the mysterious Children of Gabriel, while Abby continues searching for a way to save Kane.

Clarke fights for her life when her past catches up to her.

Octavia and Diyoza make their way to the mysterious anomaly in search of the Old Man. Meanwhile, Murphy has an offer for Emori.

While Octavia is forced to confront her past, Bellamy ventures into enemy territory with an unlikely companion.

While Gabriel must make a difficult choice, Russell seeks justice. Bellamy reunites with his sister Octavia.

Bellamy and Octavia must work together to save their friends, while Echo is forced to face her past.

A special Naming Day changes everything in Sanctum. Meanwhile, Gabriel comes face to face with an old friend.

Sanctum becomes a battleground between the devout and the non-believers, while the mystery of the Anomaly deepens.

Clarke and her friends struggle with how to proceed after the fate of the world is revealed.

The burden of leading weighs heavily upon Clarke and Bellamy when different challenges force them to determine who will live and die.

As tensions rise in Arkadia and Polis, Jaha leads Clarke and Bellamy down a road toward possible salvation.

While Abby leads a team to a distant location, hoping to find answers, the continued struggles with leadership and trust in Arkadia and Polis take a violent turn.

Clarke makes a desperate plea with a former allied force in an attempt to avoid a war and ensure the survival of her people.

Clarke and Roan must work together in hostile territory in order to deliver an invaluable asset to Abby and her team.

Clarke's arrival on the island quickly takes a turn for the worse. Meanwhile, Bellamy tries to avoid further tragedy in Arkadia.

After a disappointing discovery, Clarke and Abby question how far they're willing to go. Meanwhile, Jaha finds a lead to the mysterious Second Dawn.

Jasper and Bellamy go on a quest. Meanwhile, Clarke struggles to keep the peace after word of Jaha's discovery spreads.

Octavia fights in the final battle for her people's survival, but not everyone is willing to play fair.

Clarke faces the consequences of her fateful choice.

While Jaha and Kane disagree over how to handle their grim reality, Clarke leads a group to save a friend.

It's a race against the end of the world as Praimfaya arrives, forcing our heroes to make impossible choices to ensure their survival.

Clarke is still trapped, while the fate of Bellamy, Finn & Raven is still unknown. Meanwhile, the survivors of the Ark face a dangerous new world.

Clarke demands answers from President Wallace. Kane interrogates one of The 100, and Abby performs emergency surgery. Meanwhile, Octavia resorts to violence to find Lincoln.

Nothing is what it seems. When Clarke discovers a horrifying project being carried out in Mount Weather's medical ward, she joins forces with an unlikely ally.

After being betrayed, 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.

While Kane leads a mission to make peace with the Grounders, Lincoln enters a world of pain. And Finn's search for Clarke takes a violent turn.

Tensions run high between Clarke & Finn, while Octavia faces her worst nightmare. As Jasper & Monty discover the truth about Mt. Weather, Wallace is about to be betrayed.

Clarke comes up with a bold new plan to stop the Grounders' attack, leading Abby to a desperate decision. Meanwhile, Jasper & Monty question the motives of their new friends.

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.

Clarke strikes a deal with Lexa & Indra, while a seething Raven is unable to control her emotions. A move threatens to destroy the alliance between the Sky People & the Grounders.

Clarke and Lexa encounter a new enemy, while Bellamy and Lincoln team up to break into Mt. Weather. Meanwhile, Murphy helps Jaha confront his past, Indra makes Octavia an offer.

Bellamy and Lincoln's attempt to sneak into Mount Weather has brutal consequences, while Abby fights to stay in control as Clarke steps up in her new leadership role.

Tensions between Clarke and Abby come to a head after Clarke crosses the line. Raven helps Bellamy navigate Mount Weather, where things reach a breaking point.

Clarke begins to question Lexa's leadership decisions and Abby struggles to help an injured Kane. Meanwhile, at Mount Weather, Jasper steps up into the role of leader.

Before battle, Clarke & Lexa have a heated discussion. Desperate for help, Raven summons Wick. Jaha & Murphy encounter a perilous roadblock, while Bellamy's in a race against time.

While Clarke and Lexa prepare for battle, Octavia and Lincoln are forced to make a difficult decision.

The journey to the City of Light continues. Clarke receives help from an unexpected source and Lincoln gets his revenge.

Three months have passed since the tragedy at Mt. Weather. With a bounty on Clarke's head, Bellamy and Kane lead a team into Grounder territory to save her.

Bellamy and Kane risk life and limb to rescue Clarke. In an attempt to avoid worrying about her daughter, Abby focuses on whether to open Mount Weather as a medical facility.

Clarke wrestles with a decision. Bellamy learns that something isn't what it seems. Meanwhile, Murphy plots to betray his former Chancellor.

Clarke discovers the mastermind behind a devious plan, while Kane struggles to keep the peace. Meanwhile, Jasper's grief drives him to reckless behavior.

Clarke's hope for peace is dashed by a new threat. Raven become a target. Meanwhile, Murphy is running a dangerous con.

Clarke is torn between vengeance and mercy. Meanwhile, Kane and Octavia work together to avert a disaster, and Abby continues to worry about Raven.

While Lexa struggles to maintain peace between the clans, Clarke uncovers a strange, game-changing truth.

Searching for a peaceful way to handle things, Kane soon realizes that he may be forced to resort to drastic measures. Meanwhile, Pike suspects a leak within the walls of Arkadia.

Clarke discovers a shocking truth, and Octavia is forced to make a decision that could have devastating consequences.

Jaha employs a terrifying new method to convince Abby to join his cause. Meanwhile, Bellamy is hit with a hard truth and Monty finds himself in trouble.

Alie forces Raven's dark side to come out, while Jasper's anger continues to grow. Meanwhile, Octavia wrestles with her place in the world.

Jaha returns to Polis, and Murphy has a surprise encounter. Meanwhile, Octavia uncovers a clue.

Clarke is on a mission that could change everything. Meanwhile, Murphy gains insight that might prove useful in ensuring his survival. Lastly, Kane reaches a breaking point.

Clarke, Bellamy, Octavia and Jasper hit a tragic roadblock. Meanwhile, Raven and Monty make an important discovery.

Clarke finds hop in the most unlikely place. Meanwhile, Alie's master plan comes together.

Everyone prepares for a final showdown as they face the reality of their tragic situation.

Clarke and her friends attempt to rebuild Sanctum as a new threat rises in the woods.

Echo and Gabriel learn more about Hope and her mysterious past.

As Raven faces an unexpected threat, Clarke must keep the peace among opposing factions in Sanctum.

Mysterious outsiders arrive with news of Clarke's missing people.

Octavia gets to know a whole new world. Meanwhile, Murphy and Emori play make believe.

Clarke and her friends find themselves on a planet that is not what it seems.

Emori tries to heal Sanctum's old familial wounds while Echo, Octavia and Diyoza struggle with new ones.

While Clarke confronts a new adversary, a surprising connection takes us back to the past and the nuclear apocalypse that destroyed the Earth.

While old friends make new allegiances, Murphy and Indra must defuse a tense situation.

Sheidheda makes his move. Meanwhile, a Disciple goes rogue.

Where in the universe is Bellamy Blake?

It's a new day in Sanctum. Meanwhile, Clarke, Octavia, Raven and Echo struggle with a new foe.

The Red Sun derails Clarke's plans.

Clarke and her friends reckon with all that has happened, only to find a new unexpected threat looming.

Clarke and Octavia mount a desperate rescue mission as the Disciples close in on what they want.

After all the fighting and loss, Clarke and her friends have reached the final battle. But is humanity worthy of something greater?