In sixth-century Byzantium, enchanted by the witty and eloquent nineteen-year-old aristocrat, Princess Kassiani, the young ruler, Emperor Theophilos, decides to marry beautiful Theodora instead. On a promise of his imminent marriage to Kassiani, brave General Akyllas embarks on a military quest in Sicily, while, in the meantime, more and more, Theophilos finds himself attracted to Kassiani who has secretly started to compose religious hymns. Now, their clandestine meetings have set in motion the rumour mill, and to make matters worse, the news reaches the ears of Akyllas. As a result, the jealous fiancé defies his orders, and returns to Constantinople, bent on murder; a tragic but pivotal incident that will pave the way for Kassiani's self-exile to a monastery, and her devotion to Christianity and hymnography.