When Em's mother suddenly disappears, she is left clueless as to what happened, and what she should do. When she realizes she is a prime, the rarest of three types of people she is terrified of the responsibility she would have to fulfil. When Em finds out her world is in danger, her and the other primes are quick to prepare themselves for the greatest attack earth has ever faced. Along the journey, Em learns of the sorrow bird and the danger it brings. As tensions rise and the enemy strikes, Em has to learn to control the sorrow bird or relive the past and lose herself forever.