A small crew descends to investigate the enigmatic new planet while Monty still has them in shock. Meanwhile, back on the Mothership, a number of Wonkru members bear the repercussions of their choices.
The group battles to survive the peril that the new planet presents to them. To save everyone on board the Mothership, Raven must team up with an unexpected ally.
To secure her people's stay, Clarke makes an effort to win over the Sanctum leaders. As they work to get the transport ship back, Bellamy, Octavia, and Echo come into a new danger.
Octavia and Diyoza battle a rival group of survivors for their lives, while Clarke and the others attempt to fit in with the Sanctum.
Jordan looks inside the Sanctum. In the meantime, Octavia and Diyoza personally witness the dangers posed by the new planet, and Clarke and Bellamy engage in a conflict.
Abby is still looking for a solution to save Kane. Elsewhere, Diyoza finds out more about the enigmatic Children of Gabriel.
The past is catching up with Clarke while trapped inside her own mind, and she has to use her past to fight for her life.
In an attempt to locate the Old Man, Octavia and Diyoza travel to the enigmatic anomaly. Murphy makes Emori an offer.
Bellamy has to travel into hostile territory with a strange ally, and Octavia is compelled to face her past.
Russell tries to achieve justice; Gabriel has to make a tough decision; the Blake siblings finally get back together.
For the sake of rescuing their friends, Bellamy and Octavia must set aside their differences and cooperate. Echo is in the process of facing her past.
Everything in Sanctum is changed by a unique Naming Day. Gabriel runs into an old friend.
The Sanctum turns into a battlefield between believers and atheists. The anomaly's mystery grows more complex.