A city girl on a bus tour of the West encounters a handsome rodeo cowboy who helps her forget her city suitors.

The story picks up at the point where "The Robe" ends, following the martyrdom of Diana and Marcellus. Christ's robe is conveyed to Peter for safe-keeping, but the emperor Caligula wants it back to benefit from its powers. Marcellus' former slave Demetrius seeks to prevent this, and catches the eye of Messalina, wife to Caligula's uncle Claudius. Messalina tempts Demetrius, he winds up fighting in the arena, and wavers in his faith.

The wealthiest man in the world, John P. Merrick, is a private person who likes to stay anonymous. One of his many assets is Neeley's Department Store. There is labor unrest at the store, and the employees' anger is directed at him, who they hang in effigy outside the store despite not knowing what he looks like. Merrick, not happy at what he sees going on, decides to mete out the rabble-rousers. So he goes undercover as a sales clerk in the shoe department.

Drunk and disillusioned Roman, Marcellus Gallio, wins Jesus' robe in a dice game after the crucifixion. Marcellus has never been a man of faith like his slave, Demetrius, but when Demetrius escapes with the robe, Marcellus experiences disturbing visions and feels guilty for his actions. Convinced that destroying the robe will cure him, Marcellus sets out to find Demetrius — and discovers his Christian faith along the way.