"Shiver" is the first book in the "Wolves of Mercy Falls" series by Maggie Stiefvater. Published in 2009, it is a young adult fantasy romance novel that tells the story of Grace Brisbane and Sam Roth. The novel is set in a small town in Minnesota, where Grace has always felt a connection to the wolves that roam the woods behind her house. She particularly feels drawn to one wolf with yellow eyes. That wolf, it turns out, is Sam, a boy who was bitten by a wolf as a child and now transforms into a wolf during the winter months. Their unlikely romance forms the heart of the story. As Grace and Sam navigate their relationship, they must also contend with the dangers posed by Sam's condition and the increasing threats to the wolf population in their town. The novel explores themes of love, identity, and the struggle to find a place where one truly belongs. "Shiver" received positive reviews for its engaging characters, atmospheric setting, and emotional depth. It was followed by three sequels: "Linger," "Forever," and "Sinner," which further explore the lives of Grace and Sam and their connections to the wolf pack.