Complete story — includes the ending
Jaha leads Clarke and Bellamy on a search for a bunker built by the Second Dawn doomsday cult that could be used to survive the coming death wave; however, they discover that the bunker wasn't shielded properly and everyone inside had died. A group of grounders, including Nyko and Luna, arrive at Arkadia with signs of acute radiation syndrome (ARS) from eating contaminated fish. Abby wants to use their radiation medicine, but Raven, who is now in charge of rationing, stops her. Murphy steals it and gives it to Abby anyway. The new Flamekeeper, Gaia, steals the Flame from King Roan, but before Octavia kills her Indra stops her, stating that she is her estranged daughter. Using a decoy, Octavia tells Roan the Flame was destroyed. At the same time, Ilian leads grounders in destroying all of the technology in Polis. Arkadia can only house 100 people for the next 5 years to ride out the radiation. Clarke writes a list and includes Bellamy as number 99, and he writes her name for the 100th spot. Luna is the only person who does not die from the ARS, which makes Abby realize that Luna's body is rejecting the radiation because of her Nightblood, offering a possible solution for everyone.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, List of The 100 episodes. HTML formatting and reference markers removed. · Content license