Aster believes she is a normal teenage girl - she is very wrong . . . Teenager Aster barely escapes with her life when her adoptive father is killed in a shooting. Suddenly finding herself under the protection of a special US military unit, she learns that blood tests indicate that she's not even human. Unsure who or what she might be - or if any of this is true - Aster's first instinct is to flee. Unfortunately, she soon finds she is caught between two warring sides: on one, her mortal enemies, the alien Trackers, and on the other, the American government. Then, from the most unexpected quarter, she finds someone offering to help her - someone her instincts tell her can't be trusted . . . Now Aster can be certain of just two things: her blood is more vital than she ever knew and the fate of the world rests upon her survival.