Clarke is left on her own on the ground and she tries to make it work by first attempting to dig the bunker out of the rubble so she could be with her mother and everyone down there.
She talks to Bellamy through the radio about how everything is destroyed and there are too many rocks to actually make it down to the bunker. She ends up traveling around and suffering from hunger, dehydration, and eventually she just doesn't want to live anymore.
Before she kills herself, a bird starts to pick at her and it leads her to Eden. She finds herself in a new part of the Earth where she discovers people that didn't survive the radiation. Time passes and she finds food and time to just relax and find herself again, keeping sane with the radio.
One day she accidentally sees Madi, who doesn't want to talk to her and Clarke gets injured in a bear trap. Eventually with some patience we see Clarke and Madi start to grow together, with Clarke leaving Madi a drawing of her.
Six years later they still live there together and are waiting for the rest of her people to come down. Instead it is the prisoners transport ship.
Clarke has Madi hide but the people on the ship scouting the area find her anyway. Madi shoots at one of them and Clarke kills the other, alerting Charmaine to someone else being there with them.
In space the group is struggling with the fact that they can't get down to Earth, that is when they see the ship and decide to use up their remaining fuel to check it out. Monty doesn't want to leave, Murphy and Emori have broken up, and Bellamy is dating Echo who is worried that Octavia won't be happy about it.
Down in the bunker we quickly see the fights to the death that happen with Octavia watching from above.