Octavia fights in the final battle for her people's survival, but not everyone is willing to play fair.
Jasper and Bellamy go on a quest. Meanwhile, Clarke struggles to keep the peace after word of Jaha's discovery spreads.
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.
Clarke’s arrival on the island quickly takes a turn for the worse. Meanwhile, Bellamy tries to avoid further tragedy in Arkadia.
Clarke and Roan must work together in hostile territory in order to deliver an invaluable asset to Abby and her team.
Clarke makes a desperate plea with a former allied force in an attempt to avoid a war and ensure the survival of her people.
Continued struggles with leadership and trust in Arkadia and Polis take violent turns while Abby leads a team to a distant location hoping to find answers.
Jaha leads Clarke and Bellamy down a road to possible salvation while tensions rise in Arkadia and Polis.
The burden of leading weighs heavily upon Clarke and Bellamy when different challenges force them to determine who will live and die.
Clarke and her friends struggle with how to proceed after the fate of the world is revealed.