该剧基于休·豪伊所著同名畅销科幻系列小说改编，设定在被破坏、有毒的未来，数百层楼深的一个巨大地下筒仓中存在一个 社区，男人和女人生活在一个充满规章制度的社会里，凡是和“出去”有关的一切都成为致命禁忌。

Lynn and Lucy are life-long best friends, their relationship as intense as any romance. Neither has ventured far from where they grew up. Lynn, who married her first boyfriend and whose daughter is fast growing up, is delighted when the charismatic, volatile Lucy has her first baby boy. Lucy, however does not react to being a mother as Lynn expects. Soon, they find their friendship is tested in extreme circumstances.