Easily surviving the collapsing bridge, Zorro (Reed Hadley), who is still attempting to prevent the shipment of ammunition to Juarez (Carleton Young) from being hijacked by Don del Oro and his hirelings, lights the flaming "Z" to alert his Fighting Legion. In the meantime, Don del Oro's chief lieutenant, Moreno (James Pierce), sets a deadly trap for the wagon train carrying the ammo, which he hides in a cage. Feigning outrage, Felipe (Leander de Cordova) and his three cohorts on the council are stunned when a message from Zorro warns that he knows where the weapons are stashed. It is all a ruse, of course, and a panicking Don del Oro sends Tarmac (Joe Molina) and his Yaqui warriors to quickly move the stolen guns. Keeping track of each other by using carrier pigeons, Zorro and his men discover that Tarmac, Moreno, and Valdez (Charles King) are transporting the stolen ammo across Barrajos Pass. A furious fight ensues, during which Moreno sends a runaway buckboard filled with explosives toward the ensconced "legionnaires." As Zorro reaches the wagon, it explodes.
by Hans J. Wollstein synopsis