It is time to send the tax money to the governor, and Sergeant Garcia has a plan to thwart any attempt to steal the funds during the long journey. He orders the town blacksmith to build a huge iron box that requires a special key to open it. The money will be placed in the box and the key sent to the governor by a separate route. Two men, Nava and Crispin, learn of the plan and decide to make a duplicate key which will enable them to steal the money if they can intercept the box. They enlist the help of Moneta, a barmaid, by asking her to flirt with the blacksmith's son in the hopes he will supply a key. This plan fails when the box is completed ahead of schedule and Garcia orders the key sent on its way. During the loading of the tax money, Garcia accidentally snaps the lock shut and it must somehow be opened if the box is to be used. The blacksmith fashions a duplicate key and opens the lock, which is then placed on the box. Having seen this turn of events, Nava and Crispin try to steal the duplicate key, but Bernardo manages to keep it from them. The bandits surprise the small party of guards escorting the box, but the soldiers toss it over a steep cliff, hoping it will be inaccessible to the thieves. Undaunted, Nava and Crispin kidnap the blacksmith and his son and order the blacksmith to construct a new key right there in the ravine. Zorro had followed one of the bandits out of Los Angeles and sees the thieves standing guard over the unwilling blacksmith. The element of surprise lets him overcome the two armed men, and the box and the blacksmith are saved.
Elenco: Guy Williams , Gene Sheldon , Henry Calvin , Jolene Brand , Eugenia Paul , George J. Lewis , Guy Williams , Henry Calvin , Jolene Brand , King , Richard Anderson .