3. Earth Kills

Complete story — includes the ending

In flashbacks, Clarke's engineer father Jake discovers a life support problem with the Ark, is arrested for threatening to tell the people and " floated " by Jaha. In the present, Clarke, Finn, and Wells search for antibiotic seaweed to treat Jasper's infected wounds. Bellamy assembles a hunting group who are followed by Charlotte, a troubled 13-year-old whose parents were executed by Jaha. A lethal acidic fog hits, forcing Clarke, Finn, and Wells to seek shelter. The three talk, and Clarke berates Wells for his apparent part in her father's execution believing he told his father of Clarke's father's intent to commit treason. Bellamy and Charlotte take refuge from the fog; he comforts her when she has a nightmare. One of the 100 is fatally burned by the fog, forcing Clarke to mercy kill him; she subsequently succeeds in saving Jasper. Clarke discovers her mother's culpability in her father's death, learning that she actually told Thelonious, knowing her father would be floated. Clarke and Wells reconcile. Later, Charlotte's misinterpretation of Bellamy's advice leads her to kill Wells.