The film tells the story of a Roman military commander, Marcus Vinicius
(Robert Taylor), who is also the legate of the XIV Gemina, returning
from the wars, who falls in love with a devout Christian, Lygia (Deborah
Kerr), and slowly becomes intrigued by her religion. Their love story
is told against the broader historical background of early Christianity
and its persecution by Nero (Peter Ustinov).