The angels are guardians of paradise, the devils the guardians of the hells, and then there are the Sentinels.

The Sentinels are guardians of the realm of the living, seeking to keep mortals as free from supernatural influence as they can. They are immortal, moving through dimensions and time to keep the peace between the natural and supernatural worlds. They contend not only with demons and non-humans but also vampires, shifters, and even the gods themselves.

One of the best Sentinels, Roark Kearney, has earned himself the nickname "The Stone Sentinel." Most who casually know him would think it's because he seems like such an immovable object. A Gaelic warrior who fought in the Battle of Tara, he is one of the oldest of the Sentinels. But Julian, his "brother," knows the truth. Over the centuries, Roark has disconnected himself from his emotions over a failure that happened a millennium ago.

Now, Roark and Julian have been given a job. A young woman is in danger and needs protection. The problem is that they have no idea what is hunting her. To make matters worse, this woman seems to have a way of breaking down the walls that Roark has spent centuries building.

Can Roark do his job from a distance to minimize the impact she has on him? Or will their proximity, and her identity, be a fire that will consume them both?