"The Replacement" is a novel by Brenna Yovanoff that explores themes of identity and belonging. The story follows Mackie Doyle, a boy who is not quite human but rather a changeling, a creature swapped at birth with a human baby. As he navigates life in a small town, he grapples with his true nature and the dangers that come with it. As Mackie learns more about his origins, he discovers a dark world filled with mythical creatures and the consequences of being different. The narrative delves into his struggles to fit in while also confronting the sinister forces that threaten his existence and the lives of those he cares about.