While her friends in orbit discover a long-needed ray of hope, Clarke fights to live on an empty, destroyed planet.
When it looks like the bunker and everyone inside it are in danger, Octavia is forced to accept advice from an unexpected friend.
Bellamy takes the lead in looking for a possible return route to home.
To save some of their own, our heroes must enlist the aid of the dangerous new residents of Shallow Valley.
Octavia defies Bellamy and Clarke's advice and leads her people toward Shadow Valley.
Kane puts Wonkru's loyalty to Octavia to the test in an effort to establish his importance.
Something shocking about Wonkru's war strategies is revealed to Clarke and Bellamy.
Bellamy is forced into an impossible situation by Clarke's persistent desire to keep Madi safe.
Murphy makes life-changing decisions in the Shadow Valley, with disastrous results.
Monty wants to teach Wonkru that there is life outside of the valley and an alternative to violence. Meanwhile, McCreary's tolerance is becoming thin, and Abby's condition is getting worse.
Clarke discovers more of Wonkru's struggles in the bunker as she rushes to save Abby.
The people of Octavia declare war. Our heroes must put aside their disagreements while hidden behind enemy lines in order to prevent the annihilation of Wonkru.
When it comes to fighting one final struggle for survival, Clarke and her friends must risk everything.