It is set in Provence at three different critical moments of Western civilization—the collapse of the Roman Empire in the fifth century, the Black Death in the fourteenth, the Second World War in the twentieth—through which the fortunes of three men are followed: The story of each man is woven through the narrative, all linked by the Dream of Scipio, written by Manlius (not Cicero's eponymous classical text) and rediscovered by Olivier and Julien.

Inspired by the teachings of Sophia, a Neoplatonist philosopher and the daughter of a student of Hypatia, Manlius composes the text to justify the decisions he takes when facing attack by the Visigoths and Burgundians, with little support from Rome.

The story is narrated by an omniscient narrator, who tells the reader many things which the characters have no way of knowing such as how Olivier de Noyen, diligently searching for ancient manuscripts, narrowly missed finding the only copy of the correspondence between Manlius and Sophia, which could have become a classic comparable to the letters of Abelard and Héloïse, and how this manuscript was irrevocably lost in a fire fifty years later; or how after Julien Barneuve's death, the photo of his Jewish beloved was carelessly thrown away while the woman herself was sent by the Nazis to Auschwitz.

For example, the tenth chapter of Macrobius's commentary on Cicero's Dream of Scipio discusses how humans are dead when living, and vice versa, and how the soul ascends after its death on this Earth.

Although Chrétien lived two centuries before Olivier and in another region of France, he is described as having "the peculiar fortune of becoming the best known of the old French poets to students of medieval literature, and of remaining practically unknown to any one else.