The Changeling follows Apollo Kagwa, a rare book dealer and new father who lives in modern-day New York City. Ultimately, it is a dark fairy tale that mixes the mundanity of modern parenthood with the magical.
First, the novel talks about pivotal moments in Apollo's early life. As a small child, Apollo's father disappeared after showing him images of a mysterious island he was interested in. As an adult, Apollo becomes a father himself when his wife, Emma, gives birth to their son, Brian. One day, however, Emma tortures and murders their child and vanishes. Perplexed, disturbed, and deeply saddened, Apollo goes on a journey to find his wife and uncover why she tortured and killed their child.
He begins his journey by traveling to an island on the city's coast—the same island his father showed him photographs of. On the island, Apollo confronts supernatural entities, his own personal demons, and other demonic influences that threaten to destroy his life. As he learns more, Apollo uncovers dark family secrets and a troll, which he eventually kills. Because of this, he also learns that the being Emma killed was a changeling and that she and his real child are out and about, living in the city. And he has to find them before it's too late, which he ultimately does.
Predominantly, the novel explores the layered aspects of fatherhood. Apollo's own experiences, shaped by the absence of his father and his struggles to be a present and caring parent, offer readers a unique look at masculinity and paternal love when someone doesn't have a parent around. By contrasting Apollo's dedication to his child with the haunting past of his own father's disappearance, LaValle underscores the cyclical nature of father-son relationships (and abuse) and the tremendous effort that is often required to break free from past traumas.
The novel is also a sharp critique of the digital age. In an era of constant surveillance, social media, and digital communication, the novel shows the advantages and pitfalls of being able to connect with people so quickly and easily. Technology helps Apollo; however, it is also a tool for surveillance and control. The powers at play use technology to monitor Apollo and his progress, illuminating the concerns many people have about the role that technology plays in our everyday lives.