In upstate Idaho, Ness Hook is run out of his mom's house by his bullying brother Shawn. In Redding, California, Tristan Carter is graduating college, but with no job and no prospects, she'll have to move back in with her parents. Then the world ends.
After Ness discovers his best friend dead of disease, Shawn takes their family to the mountains to wait out the plague.
As Tristan's parents fall sick, she's left to care for her younger brother, Alden. Both sets of siblings dig in for the long haul. Humanity is reduced to splinters. And then the creatures who sent the virus appear in the sky. Flushed from the mountains, Shawn and Ness join a tribe at a nuclear power plant, where they plan to launch a guerrilla war against the invaders. In California, Tristan and Alden are taken prisoner. Separated from her brother, Tristan crosses the ruins of America to track him down. She will stop at nothing to get Alden back - but her fellow survivors prove even more dangerous than the monsters who broke the world.