Narrated by siblings Nick and Lily, the story follows their resourcefulness in aiding neighbors. Nick's digging prowess and Lily's strategic planning become vital as oxygen diminishes. Nick unveils a hidden tunnel connecting houses, forming a lifesaving network as breathable air dwindles. Lily crafts a communication system with walkie-talkies and baby monitors to share critical information. A frantic race ensues to complete the tunnels before food and oxygen become scarce, a tense battle for survival in a world teetering on the brink.