Ninety-seven years after nuclear Armageddon destroyed our planet, humanity's sole survivors live on the Ark, an aging space station experiencing overpopulation and inadequate resources. When faced with difficult choices, the Ark leaders - chief medical officer Abby, Chancellor Jaha and the mysterious Kane - decide to send 100 juvenile prisoners back to Earth to test it's living conditions. Among them are Clarke, Abby's bright daughter; Wells, Jaha's son; the daredevil Finn; and siblings Bellamy and Octavia.