What happens to a pony when he has to fight those who took away his family?
Can a Changeling fight for his friends against his own kind, and keep his race a secret?
Coast's hometown is the sight of the beginning of a massive changeling invasion. His brother, and best friend, is kidnapped and replaced by a changeling who tries to pull off the disguise and fit in to pony society.
Through war, a small group and some friends attempt become close, and stay close, to find a way to stop the spreading Swarm.