On a cold, winters night in London yet another priest has been butchered. Inspector Maggie Maguire finds the crime scene all too familiar, no clues or any idea who could cause such carnage. There she meets a mysterious church envoy, Lucas Olsen, sent from Rome to carry out his own investigation, and he’s not the type for sharing information. Only when Lucas is badly injured, barely surviving an attack, does he have no choice but to confide in her, not only about his mission but also his past.
He tells her of Lilith, one of Lucifer’s Fallen Angels, and how she is trying to return to Earth to take her revenge. Of how he is a member of a secret order, The Contengo, ex-military who are pledged to fight evil wherever it surfaces, and at whatever the cost.
She laughs at his story. Maggie’s faith has long since disappeared, months of watching her husband waste away in a hospital bed have put paid to that. Day by day it starts to dawn on her that he may be telling the truth and together they search for her and her followers.
As the true extent of how far Lilith’s influence reaches becomes clear, Maggie and Lucas realize the only have each other. Unable to trust the police or the Church, they must stop her before she gives birth and pure evil takes human form.