After his father, Constantius (Carlo Ninchi), loses his life in battle, Constantine (Cornel Wilde) becomes the new Emperor of Rome. Emperor Constantine fends off attacks from his jealous enemy Maxentius (Massimo Serato), meanwhile adopting Christianity and establishing religious tolerance. Based on actual events, this Italian adventure film also stars Fausto Tozzi, Christine Kaufmann, Belinda Lee and Tino Carraro.