Naples, Italy 1600: In a desperate attempt to avoid an undesirable fate, “Carlo” dispatches an urgent letter to his estranged cousin, Giovanni Balducci, on the eve of the Florentine Maestro's departure to Naples. The deceptive youth convinces Giovanni that he needs an apprentice, so they travel south to complete important commissions, including the adornment of the macabre San Gaudioso catacombs. What began as an adventure takes a perilous turn when the apprentice falls in love with a local monk.

Carlo meets the famed nun, Sister Giulia di Marco, and her confessor, Father Aniello Arcieri, a few years later, while restoring an altarpiece in a church. The charismatic pair gradually draw the lonely artist into their scandalous Confraternity of Carnal Charity, whose wealthy noble acolytes believe divine glory can be achieved through sexual ecstasy. Unable to continue living a lie, Carlo confesses a big secret to Sister Giulia. The crafty nun wastes no time assigning the novitiate a prominent role within the cult, which soon captures the attention of the Holy Inquisition. To make matters worse, the priest leading the investigation is someone the artist knows all too well.

This gripping account of forbidden love and danger revolves around actual historical accounts. The author has spent considerable time researching in Naples, especially within the mysterious and bizarre underground catacombs.