Kira, Jed and their friends have fled New Corporation and joined the Resistance, but their relief is short-lived as they discover how decimated the human race has become and learn of an environmental crisis that threatens to destroy their existence. Kira and Jed must travel up the mountain to the New Corporation stronghold, City 50, to bargain for sanctuary while Martha and Dina risk everything to return to City 42 and save those who are left. With the last of her reserves Gaia, the fading spirit of the Earth uses her remaining influence to guide Kira and her friends but ultimately, it's up to humanity to make the right choice.