Plot summary
Bellamy's group along with Madi, Octavia, Gaia, and Indra return to Wonkru. Octavia publicly submits to Madi, unifying Wonkru under Madi's command. Clarke frees Diyoza and holds her and McCreary's unborn child hostage, grounding the transport ship. Bellamy's group freely enter the gorge and take out its defenses, clearing the way for Wonkru. McCreary triggers a protocol that will destroy the valley before he's killed by Clarke. Octavia helps Abby get Kane to safety. Everyone on Earth flees the planet and head towards the Eligius mothership before the valley is destroyed.
Everyone decides to enter cryogenic sleep for 10 years in order to give Earth time to recuperate. Clarke and Bellamy awaken first and are greeted by Jordan, the son of the now-deceased Monty and Harper, who had elected to not undergo cryostasis. They're informed by Jordan that 125 years have passed and through a series of video diaries left by Monty and Harper they learn that Earth never fully recovered. However, Monty managed to hack the Eligius Three mission file, leading to the discovery of another planet on a distant binary star system where he sends the survivors prior to his death.
Credits
Adapted from Wikipedia contributors, List of The 100 episodes. HTML formatting and reference markers removed.