Callista is set in the mid-3rd century in the city of Sicca Veneria in the Roman province of Africa. It deals with the persecution of the Christians community under Emperor Decius. Callista is a young and beautiful Greek girl who works for Jucundus, uncle of a troubled young man named Agellius, carving statues of pagan gods. She is a gifted young woman, yet she is unhappy with her life. Christian Agellius wants to marry Callista, but he is torn between his faith and his family who want to bring him away from the Christian faith. After a terrible plague of locusts, popular rage against Christians breaks out and persecution starts once again.