When Ruby is entrusted with an explosive secret, she must embark on her most dangerous mission yet: leaving the Children's League behind. Crucial information about the disease that killed most of America's children, and turned Ruby and the others who lived into feared and hated outcasts, has survived every attempt to destroy it. But the truth is only saved in one place: a flashdrive in the hands of Liam Stewart, the boy Ruby once believed was her future and who now wouldn't recognize her.