Androcles is a Christian who follows that religion's teachings even as they apply to the treatment of animals. Seeing a lion in pain, he removes a huge thorn from the beast's paw, creating a friend for life. Androcles and a number of other Christians are evenutally arrested and condemned to death in the arena. They are to die by being eaten by lions. Is it too much to hope that one of the lions may have a paw that has healed recently and might remember who helped heal it?

In Rome, during the reign of Antoninus, known as Caesar, Cato, the head of the secret police, conveys orders to the army to capture one hundred Christians per week for sacrifice at the imperial circus. When soldiers arrive in Syracuse, Androcles, a meek Christian tailor, and his shrewish wife Megaera abandon their home to avoid arrest. While fleeing through a forest, Androcles and Megaera encounter a lion, whose roar causes Megaera to faint with terror. The animal-loving Androcles, however, notices that the lion has a large thorn stuck in its paw and gently removes it. Androcles and the grateful lion, whom Androcles names Tommy, are cuddling and playing with each other when two soldiers approach and recognize Androcles. A revived Megaera escapes into the woods, but Androcles is captured and labeled a sorcerer because of his seemingly unnatural rapport with the lion. Later, Cato warns a captain who is escorting Androcles and other Christians to Rome to maintain a tight reign on his prisoners, as they are known to be effective persuaders. When the Captain notices the beautiful, devout Lavinia tending to a wound on one of his soldiers, he dutifully reprimands her, even though he is attracted to her. Lavinia, who has befriended Androcles, laughs at the Captain's threats, pointing out that either way, she is doomed. Soon after, a wagon topples onto a soldier, pinning his leg. Without hesitation, the chained prisoner Ferrovius uses his great strength to lift the wagon. In gratitude, the Captain orders Ferrovius' chains removed, ignoring warnings about his ferocious temper and uncanny ability to convert people. While camped that night, the Captain flirts with Lavinia and offers to save her, but she resists his help. When the hymn-singing group arrives in Rome, Lentulus, one of Caesar's supporters, decides to test the Christian philosophy by slapping Ferrovius' face to see if he will "turn the other cheek." Ferrovius controls his anger, but insists on performing the same test on Lentulus. Preaching wildly, Ferrovius hits Lentulus, who is too terrified to strike back and faints. The prisoners then are escorted to the Colosseum, where the men are to battle Roman gladiators and the women are to be devoured by lions. At Caesar's palace, meanwhile, the emperor discusses the Christian problem with Editor, the circus' overseer. Although Editor complains that the Christian sacrifices ruin the circus, Caesar declares that it is his destiny to make martyrs of the zealots. Caesar then informs the traitorous Spintho, a crony who has secretly converted to Christianity while stealing from the Roman temples, that his "sickness" will soon be cured. Spintho is arrested and thrown in with the other Christians at the Colosseum. On the eve of their circus appearance, Ferrovius wonders if he can be "faithful till the end," while Lavinia reasserts her faith and once again declines the Captain's offer of help. Confident in the promise of the hereafter, Lavinia and Androcles both refuse to burn incense at goddess Diana's temple, a symbolic act that would save their lives. The cowardly Spintho, however, runs to the temple to denounce Christianity, but is eaten by a lion instead. When the circus finally begins, Ferrovius grabs a sword and, in front of the blood-thirsty crowd, fights the gladiators. While Ferrovius downs man after man, the Captain makes a final plea to Lavinia, begging her to marry him. Noting that she is not dying for her religion but for something greater, Lavinia turns down the Captain. Caesar is so impressed by Ferrovius' fortitude that he declares that all of his subjects should convert to Christianity and orders that only one prisoner be thrown to the lions. Because of his reputation as a sorcerer, Androcles is selected, but to the surprise of the crowd, the lion, Tommy, recognizes Androcles and starts to dance with him. Caesar corners the pair inside the arena, and Androcles shows the emperor how to befriend the lion. Once Caesar has Tommy in an embrace, he calls to the others and announces that he has "tamed" the lion. Ferrovius then accepts a position as an imperial guard, while Lavinia and the Captain look forward to a happy future together. Granted their freedom, Androcles and Tommy stroll merrily away.