After witnessing her fiancé's murder and almost dying herself, Vivien Kelly's mission is to destroy Dagda—a Celtic God turned demon. As a supernatural dark cloud looms over the Sahara, she finds herself drawn to the Northern California town of Half Moon Bay and a new life as a paranormal cleanser. There Vivien finds Dagda's creatures tormenting the locals. Her own paranormal cleansing team—The Kelly Society— is born, and the race is on when people around her begin to die.

While banishing a Banshee, Vivien meets Neal Harrington—a soul partner who can promise true happiness. But when Dagda's black vapor creates a New World of darkness, her time is up. Can Vivien abandon everyone she loves and succumb to her past life's barbaric force to defeat the demon? Her actions not only determine her future—but the future of the modern world.