Kane takes part in a mission to make peace with the Grounders. Jasper decides to take part in a risky experiment. Lincoln enters a world of pain and President Dante Wallace issues a warning.

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

Alie forces Raven’s dark side to come out, and Jasper’s anger continues to grow. Meanwhile, Octavia wrestles with her place in the world, and Monty is forced to make a split second decision.

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

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

Still reeling after receiving Monty’s message, a small group goes down to explore the mysterious new planet. Back on the Mothership, several members of Wonkru face the consequences of their decisions.

Sanctum becomes a battleground between the devout and the non-believers. The mystery of the anomaly deepens.

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

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