In 4th-century Rome, a Christian slave named Vibio (Lang Jeffries) refuses to fight as a gladiator. His master’s daughter, Fabiola (Rhonda Fleming), whips him for his insubordination, but her cousin's (Wandisa Guida) kindness toward him inspires Fabiola's pity. With her help, Vibio and his fellow slaves instigate a massive uprising against their owners. Inspired by true events, the story is loosely based on Cardinal Wiseman's novel Fabiola.