Sixteen-year-old Phoebe Pope has enrolled at the Campus Below: a spy academy for shape-shifters hidden deep beneath the grounds of a boarding school whose humans unknowingly protect it. There, thanks to a carefully planned schedule, she leads a double life: spy trainee Below and normal teenager Above. As if two course loads, concealing a secret power she alone wields, and coping with her father’s recent death weren’t enough, Phoebe finds herself developing major feelings for actor and teen heartthrob Colten Chase, who attends the Campus Above and appears to be majoring in winning Phoebe’s heart. But when officials learn that Phoebe may be at the center of a startling prophecy, she becomes the target of shape-shifting assassins who will stop at nothing to suppress the truth. Now Phoebe’s lessons about Shaper’s enemies and spycraft take on great importance as a menace stalks the campus, with Phoebe as its target. Meanwhile, what began as an unlikely relationship with Colten, quickly morphs into heartache when she suspects that something sinister lurks beneath this movie star’s glitter and fame. Suddenly, Phoebe’s caught in a mesh of lies, betrayals, and danger where she doesn’t know who to trust, and needs to rely on herself—and her secret power—to get to the truth and to stay alive.