The Circle Book One of the Sidhe Series

Calum Ranson is sure of three things: his cousin Finley is alive, Calum will find him, and no one knows Calum and his family are Sidhe. No one until Laurel shows up at his mother's bookstore wearing a dark clan's mark. When Calum learns the details surrounding the disappearance of Laurel's brother, he suspects the evil Hobayeth clan. Calum and Laurel work together in the Realm of Man and the Otherworld to rescue her brother-revealing a connection between Calum and Laurel that may cost Finley his life.