The Greco-Venetian Dominican monk Giovanni (secular name Jean le Clerc) travels as an envoy of his order from Venice to Constantinople, leaving behind an enviable career as a police chief in the city of the doges. He will arrive at the monastery of Saint Athanasius, outside Byzantine Karitena, where he will meet an old friend from Venice, Constantine.

The next morning, however, the monks will discover their elderly abbot dead. Then, they will be astonished to hear their Dominican guest claim that the abbot was murdered, and Constantine, as the new abbot, will assign him the investigation. However, some within the monastery have no interest in the investigation proceeding.

During the investigations, Jean will uncover the greatest secret of Christianity hidden within the dark rooms of the monastery. He will immediately realize that everyone's life is in danger, as the murderer is lurking and watching him.

A thrilling medieval mystery story, set against the backdrop of the Peloponnese during the era of Constantine Palaiologos, that will captivate every lover of Greek fiction.