When Homicide Detective Kara Gillian finds traces of arcane power on a body, she quickly realizes that this is no ordinary murder. The serial killer known as the Symbol Man is a nightmare that Beaulac, Louisiana thought had ended three years ago, but now he's back for an encore and leaving every indication on the flesh of his victims that he is well-versed in demonic lore.
However, Kara is a Summoner of Demons, and may be the only cop on the city's small force who can stop the killer. Able to see and interact with a world most people can't, Kara soon discovers that the Symbol Man is also a summoner, one who seeks to gather enough arcane potential to summon a Demonic Lord--a potent entity who, if bound, would give the killer nearly unlimited power.
But Kara has encountered this Demonic Lord before and has been unwillingly marked as the Lord's own. With the aid of an FBI agent who may be more than he seems, Kara must stop the killer and keep the Lord from being summoned, all while defying the same Lord's demands that she call him to her--an action that could bring new and terrible meaning to the phrase "Hell on Earth."