Morgan Kingsley does exorcism, it’s a calling not a job. When she goes to Philadelphia perform an exorcism, it turns nasty fast. The locals don’t follow protocol and let the family of the little girl hosting the Demon, and the demon is almost too strong for Morgan and they have to get the family out before it touches someone and takes over a new host. Morgan defeats the demon and passes out and when she awakens she is in the same room, but locked in. When she asks to be released she is told that she will be released only when they have someone check her out to make sure she is not hosting a demon.
She is released when they find out she is not hosting a demon, when her best friend comes out to read her. When she is back home weird things start to happen. She tarts to leave herself notes in her sleep. That it is not a dream and that it is real. She is hosting a demon and his name is Lugh and he communicates to her in her dreams. He is the next in line to be King of the demon realm.
They must find out who is behind implanting Lugh into Morgan, and they must race against the clock while keeping the rival demons at bay before they kill Morgan.