6. His Sister's Keeper

Complete story — includes the ending

This episode's plot summary may be too long or excessively detailed. Please help improve it by removing unnecessary details and making it more concise. ( September 2020 ) ( Learn how and when to remove this message ) In flashbacks, Bellamy witnesses Octavia's birth. Due to the Ark's one child rule, Octavia is forced to live beneath the floor of her family's quarters. When Octavia is 16, Bellamy takes her to a masked ball for Unity Day. She is caught, and their mother is floated. A year later, Commander Shumway convinces Bellamy to assassinate Jaha in exchange for a place on the dropship with his sister. In the present, Bellamy assembles a search party for Octavia, and they leave for the woods. The group is ambushed by grounders, resulting in three deaths before they are suddenly called off by a foghorn. Clarke and Raven travel to Finn's bunker in hopes of finding a radio transmitter with which to contact the Ark, and Raven discovers Finn's involvement with Clarke. Bellamy, Finn, and Jasper rescue Octavia who has been protected by the grounder who captured her. Finn discovers that the grounder was the one who called off the attack. Seconds after that the grounder stabs him. Jasper hits the grounder unconscious. As a storm approaches, Clarke warns that she can only save Finn with her mother's help and they must repair the radio.