A changeling who has lived at the side of an Equestrian mare for most of his life finds himself in the middle of the changeling invasion of Canterlot. He has no idea who the invading queen or hive are, and just wants to stay where he is, and more importantly, who he is.
The spell that ends the invasion doesn't discriminate, though. With his old pony form irreversibly stripped away, and the whole kingdom out to hunt his kind, he tries to keep his family together, and struggles to find his place in the world.