In 1469 Tuscany, when Dario Rossi, a hedonistic city ruler, sees a vision of himself writhing in eternal flames, he is shaken to his core.

Desperate to avoid damnation, Dario pleads with Amadeo, a righteous builder, to absolve his sins by constructing the world’s largest cathedral. But Amadeo has heard the rumors-about the women streaming nightly through the palazzo, the murders, and the disappearances. How he longs to build such a monument to God! Though it will consume a lifetime, he agrees to the task.

But as Dario watches the pious builder direct his artisans and the walls rise, the contrast between the two rankles. For Dario is a slave to pleasure, debauchery, and power. When his disgust at the man’s virtue finally boils over, he schemes treachery and plots the builder’s moral downfall.

A chance meeting throws Amadeo with the beautiful, fun-loving Simona, and he’s enchanted. Though she declares her love and pursues him, he clings desperately to a vow of chastity.

As the work proceeds, Naples declares war, and Dario runs out of money. When Amadeo’s unpaid workers fear invasion and flee the city, he gives in to despair. Then the cardinal begins an Inquisition against heretics, and friends warn the builder to stop questioning Church doctrine.

Will Amadeo avoid Simona’s advances, Dario’s temptations, and the coming Inquisition? Will he finish his great work before he dies? Or will Dario undo everything?