Lilly and Brand's daughter, Caylin, saw her soul mate for the first time when she was fourteen years old. After a simple exchange of smiles, she knew her life was set on a path which would lead Aiden back into her world forever. For three long years, Aiden keeps his distance from Caylin out of respect for her parents' wishes. Being a Watcher who once gave into the dark side of his curse, Aiden uses the time to come to terms with his own demons and strives to become a man worthy enough for the granddaughter of an archangel. Caylin learns that one of the Princes of Hell, Baal, is out to kill her. With the help of her family and Aiden, she discovers why he wants her dead and what she needs to do to stop him and the other princes from destroying not only her future but the future of the world.