The climate apocalypse has come and gone, and in the end it wasn't the temperature climbing or the waters rising. It was the trees. They created enough pollen to render the air unbreathable, and the world became overgrown.
In the decades since the event known as the Turning, humanity has rebuilt, and Izabel has grown used to the airtight domes that now contain her life. She raises her young daughter, Cami, and attempts to make peace with her mother's death. She tries hard to be satisfied with this safe, prosperous new world, but instead she just feels stuck.
And then the tranquility of her town is shattered. Someone—a serial killer—starts slashing through the domes at night, exposing people to the deadly pollen. At the same time, Cami begins sleep-talking, having whole conversations about the murders that she doesn't remember after she wakes. Izabel becomes fixated on the killer, on both tracking him down and understanding him. What could compel someone to take so many lives after years dedicated to sheer survival, with society finally flourishing again?