All her life, Spensa's dreamed of becoming a pilot and proving herself a hero like her father. She made it to the sky, but the truths she learned there were crushing. The rumors of her father's cowardice are true--he deserted his Flight during battle against the Krell. Worse, though, he turned against his team and attacked them.

Spensa is sure that there's more to the story. And she's sure that whatever happened to her father that day could happen to her. When she made it outside the protective shell of her planet, she heard the stars--and what they revealed to her was terrifying. Everything Spensa has been taught about her world is a lie. 

Humankind has always celebrated heros, but who defines what a hero is? Could humanity be the evil the galaxy needs to be protected from? Spensa is determined to find out, but each answer she discovers reveals a dozen new questions: about the war, about her enemies, and even, perhaps, about Spensa herself.

But Spensa also discovered a few other things about herself--and she'll travel to the end of the galaxy to save humankind if she needs to.