The.100.S02E09.720p.English-

In the second season, the remaining 48 of the 100 are taken by the Mountain Men to Mount Weather, where they discover a community of survivors. It is eventually revealed that the Mountain Men are transfusing blood from imprisoned Grounders as an anti-radiation treatment. Medical tests of the 100 show an even more potent anti-radiation efficacy; their bone marrow will allow the Mountain Men to survive outside on the ground. Meanwhile, the inhabitants of the Ark have successfully crash-landed various stations on Earth and begun an alliance with the Grounders to save their groups of people, naming the main settlement at Alpha Station "Camp Jaha".
Jason Rothenberg and is loosely based on the book series of the same name by Kass Morgan. The series follows a group of Delinquents, who have been sent down to Earth to see if it is survivable or not. For the first time in nearly a century, humans have returned to planet Earth, but they realize they're not alone.
Set in 2149, 97 years after a nuclear apocalypse has devastated the surface of Earth, the only survivors were approximately 400 inhabitants of 12 national space stations that were in orbit at the time. Three generations have survived in space. The Ark has strict measures, including capital punishment for those over 18 and population control, as the leaders of the Ark take steps to ensure the survival of the human race. But now, resources are running out and the Ark is dying. For the first time in nearly a century, there is talk of returning to Earth.
100 juveniles convicted of various crimes are sent to Earth to see if it is survivable. Among them are 17-year-old Clarke Griffin, the daughter of the Ark's chief medical officer and of the Ark's chief engineer; Wells Jaha, the son of Chancellor Jaha; the daredevil Finn Collins; the illegal sister Octavia Blake; her stowaway brother Bellamy Blake; the lighthearted Jasper Jordan; and the resourceful Monty Green.
Technologically blind to what’s happening to the 100 on Earth, the Ark’s leaders Chancellor Jaha, second-in-command Marcus Kane, Councilwoman Abigail Griffin and the Council are faced with difficult decisions about life, death and the continued existence of the human race.