Their families dead from the pandemic SitkaAZ13, known as "Pest," 15-year-old cheerleader Clare and 13-year-old chess club member Jem are thrown together. They realize that, if either of them wishes to reach adulthood, they must find a cure. A shadowy adult broadcasting on the radio to all orphaned children promises just that-to cure children once they grow into Pest and then to feed and care for them.

Or does this adult have something else in mind? Against a hostile landscape of rotting cities and a countryside infected by corpses and roamed by diseased and doomed survivors, Jem and Clare make their bid for life. As their group of fellow child-travelers grows, they embark on a journey to find the cure. In their search, they are hampered by the knowledge that everything in this new world has become suspect-adults, alliances, trust, hope. But perhaps friendship has its own kind of healing power. And perhaps, out of friendship, there can come love.