Callie is deep in the Zone - exposed, broken and alone. Without her little sister Gracie. Without Matt, the boy she loves.

But when she stumbles upon a secret - hidden deep within herself - she realises that she holds the key to defeating the Change.

But the Change know this too and they will stop at nothing to capture her.

Fleeing from the officers of Quarantine, and the pervasive Change, Callie finds refuge in the unlikeliest of places.

Only to find that she is in more danger than ever before.