The peace between Mexico and the United States has been endangered from time to time by the greedy plots of sinister groups. The reign of terror inspired by one such group is our story, and into this Zorro rides again.
Marsden, a financial pirate ruthlessly determined to destroy the California-Yucatan Railroad, is aided by El Lobo whose forces reign terror on the project hoping to force the sale of the railroad to Marsden. James Vega has other ideas.
El Lobo attacks Ocilla Junction with the goal of destroying the railroad's supplies. Joyce and Philip Andrews courageously defend their holdings in the railroad, while Zorro attempts to prevent El Lobo from bombing the warehouse.
Tricked by James into replacing supplies for the California-Yucatan Railroad, Marsden orders El Lobo to wreck the supply train, a feat he attempts to accomplish by opening a derailing switch ahead of the oncoming train.
Marsden orders El Lobo to tap the railroad company's telephone. Then, disguised as Zorro, El Lobo murders Senor Lerda and steals the deeds to his property. After recovering the deeds, Zorro is tricked into returning them to El Lobo's men.
Marsden plans to stop construction on the railroad by concealing the deeds to Lerda's property. Zorro captures two of El Lobo's men but fails to recover the deeds. James then disguises himself as one of El Lobo's men to complete the task.
Marsden orders El Lobo to capture Zorro. To succeed in the endeavor, El Lobo first raids Ocilla Junction, capturing Philip and Joyce in the process. Joyce is soon sent to deliver a message to Zorro, who in turn plots a rescue with Renaldo.
El Lobo is forced to surrender evidence of his connection with Marsden to Zorro. Philip and Joyce fight desperately to complete the main line of the railroad. Zorro gives warning that El Lobo plans on attacking Ocilla Junction.
Marsden orders El Lobo to destroy the water system. To do so, El Lobo plans to open the floodgates at the Perdita Dam. Philip and Joyce question James' apparent lack of concern towards El Lobo's crimes, forcing Renaldo to defend him.
Outwitted by Zorro, Marsden orders El Lobo to mine Tunnel 13 ahead of Philip and Joyce's inspection train. James gets wind of El Lobo's plan and prepares for a dangerous mission. After evading capture, Zorro hurries to warn the Andrews.
Marsden and El Lobo hatch a shrewd plan that eventually leads to the Andrews signing away their entire holdings in the railroad. James decides to visit Marden's office. Renaldo locates the deed to the railroad, which is recovered by Zorro.
Marsden plans to steal the records of the railroad company, prompting Philip and Joyce to take the records to Mexico City by train, but El Lobo and his men board the train at a water stop. Will Zorro be able to prevent the train robbery?
