The epistolary narrative follows Lucius Manlius Piso, a Roman aristocrat residing in the capital after his connection to the fallen Queen Zenobia of Palmyra. Piso startles Roman society by openly adopting Christianity and decorating his library with statues of Moses and Christ rather than traditional pagan deities. His conversations with his stoic mother Portia, the philosophical Probus, and the prefect Varus reflect the deep ideological fault lines of an empire in crisis. Concurrently, Aurelian's domestic policies and extravagant displays mirror his shifting anxieties, particularly surrounding the restless nobility and the growing Christian population.
The historical tensions culminate during the grand dedication of the Temple of the Sun, where mysterious omens and a supernatural voice interrupt the ceremonies. Aurelian, goaded by the fanatical priest Fronto, becomes increasingly convinced that the Christians are responsible for the divine displeasure threatening Rome. Amidst street violence, public executions, and mounting political paranoia, Piso and his allies struggle to defend their faith against the brutal machinery of imperial persecution. The narrative provides a vivid, detailed window into the intellectual and social chaos of an era on the brink of profound transformation.