After railroad agents forcibly evict the James family from their family farm, Jesse and Frank turn to banditry for revenge.
One of the last bills signed by President Lincoln authorizes pushing the Union Pacific Railroad across the wilderness to California. But financial opportunist Asa Barrows hopes to profit from obstructing it. Chief troubleshooter Jeff Butler has his hands full fighting Barrows' agent, gambler Sid Campeau; Campeau's partner Dick Allen is Jeff's war buddy and rival suitor for engineer's daughter Molly Monahan. Who will survive the effort to push the railroad through at any cost?
The mysterious Don Del Oro ("Lord of Gold"), an idol of the Yaqui Indians, plans to take over the gold and become Emperor. Francisco was put in charge of a legion to combat the Yaqui tribe and protect the land, but when attacked Zorro came to his rescue. Francisco's partner recognized Zorro as the hidalgo Don Diego Vega, then ask him to take over the fighting legion as his alter-ego Zorro.
