When Leone Scamarcio investigates the murder of a boy with demonic possession, who will win: Scamarcio or the Devil?

On a cold and wintry Roman afternoon, a troubled young man, Andrea Borghese, is found dead in his parents' apartment. The last people to see him alive were five Roman Catholic priests who had left the Vatican to visit Andrea for a very particular purpose. They were performing an exorcism.

Meanwhile, Detective Leone Scamarcio is unravelling. His partner, the beautiful ex-showgirl Fiammetta DiBondi, is expecting their first child, and the baby is due any day. But what kind of world is this in which to raise a child? When his boss, Chief Garramone, calls with the Borghesi case, insisting that Scamarcio is the only man he trusts with the job, Scamarcio accepts the mission as a welcome distraction.

But the case proves far more tangled than Scamarcio had anticipated, and he finds himself in an ever-thickening plot of occult practices, murder, church corruption, government bribery, pharmaceutical dirty dealings, family secrets, and, of course, the mafia. To make things even more complicated, Scamarcio's old flame, Aurelia, has returned to Rome, and Scamarcio is having trouble thinking straight. As he circles closer to the truth, the danger mounts, and when his new little family comes under threat, Leone Scamarcio has to decide once and for all what he really stands for.