The character of Zorro has been in many films, most notably Douglas Fairbanks's "The Mark of Zorro" (1920) and the 1940 remake with Tyrone Power. Republic studios made many serials with the character, most of them with the company's usual "improvements".
Jeff Stewart (George Turner), a rancher and lawyer, is returning home to Box County now that the Civil War is over. He sees the postmistress Kate Wells (Peggy Stewart) apparently at the mercy of a runaway buggy. Rushing to save her he finds out that she was in control the whole time. She is in a hurry to get a back tax payment to the Sheriff before he auctions off her uncle's ranch.Jeff takes over the reins and double times it to the ranch but is too late, the ranch had just been auctioned off. Jeff comes to the man's defense which gets him into a fight. Crooked Sheriff Moody (Edward Cassidy) arrests Jeff for the fight and brings him before the crooked Judge Hyde (Ernie Adams) who fines Jeff a hundred dollars.
What no one knows is that both men are controlled by a mysterious leader.
As Kate drives Jeff home she tells him how the crooked politicians are bleeding the county dry with exorbitant taxes and a huge toll on the main highway. Plus they also allow a gang of outlaws led by Boyd (Roy Barcroft) to have complete immunity in the county as they rob the surrounding territory.
Arriving at his ranch Jeff learns from his servant and friend Pancho (Stanely Price) that the Sheriff had taken all of his stock in lieu of tax payments. Pancho was able to hide the horses in a nearby valley. Pancho feels jeff should assume the guise of his ancestor Zorro and mete out justice the old fashioned way. Jeff prefers to try legal methods first.
The next day Jeff meets Kate at the general store which houses the post office. He is introduced to cheerful and helpful store owner Daniels (Tom London) and his checker rival, grumpy ranch owner Stockton (Edmond Cobb). Jeff tells them that he has been granted by the Governor the right to build a new road that will cut off before Box County so no tolls will have to be paid.
As work on the road starts Jeff learns that Boyd and his men plan to destroy all the supplies and kill all the workmen. Deciding Pancho is right, Jeff dons the black garb of his ancestor Zorro and rides off to save the supply wagons. he is unsuccessful. Even worse, he and Kate are trapped at a wagon full of explosives in a cul de sac that Boyd has been able to set on fire.
Kate and Zorro escape the explosion due to a recess in cul de sac wall. With no money or supplies Jeff goes to gold mine owner Baldwin (Wheaton Chambers) to see if he will supply the needed money. Baldwin would like to help but the taxes on exporting gold out of the county is too high to pay. Jeff comes up with the idea of using his horses to pack the gold over the mountains. Baldwin agrees to the plan. Boyd gets wind of the plan and tries to attack Jeff and take his horses but Jeff tricks them into following an empty horse pulling a branch to stir up dust.
Realizing they've been tricked Boyd leads the gang to the mine to steal the gold. Zorro arrives and a fight breaks out. Kate is knocked unconscious in the path of the revolving millstone used to crush ore. Zorro manages to pull her to safety just in the nick of time and drive off Boyd.
Days later Jeff visits Kate at Daniels store. He has gotten money for the gold and is on his way to the bank to deposit it. Just then the Sheriff walks in demanding the money by order of the court for taking gold out of the county illegally. Jeff outsmarts Moody by giving the money to Kate as part of the outgoing mail.
Sheriff Moody arrests Jeff but he easily escapes. Judge Hyde puts a thousand dollar reward for his capture. Later that night Boyd ties up Kate and prepares to blow open the post office safe. Jeff, aware that the mail has been stolen in the past, changes to Zorro and goes to retrieve his letter for safe keeping. he and Boyd get into a donnybrook that tears the store apart. Zorro just barely manages to roll out of the way when the two ton safe is blown off it's hinges.
Defeated once again Boyd hightails it for safety while Zorro unties Kate. Jeff gets the money to the bank and is again ready to start work on the new road.
The serial is rather pedestrian, the old corrupt officials running the town for personal profit, is a standard of the genre. The addition of a mystery leader is an added boost to keep interest going through the thirteen chapters. but since there are only two suspects, one friendly and one eternally pessimistic, it doesn't take a serial buff worth their salt to figure out the culprit's identity.
Thankfully there is plenty of action with chases, shoot outs, fist fights, and exploding wagons. Something Republic did better than anyone else. Another bonus is the familiar faces doing what they do best; Barcroft being nasty, Ken Terrell as the shifty eyed store clerk, and Ernie Adams, the epitome of the weaselly henchman.
George Turner as the hero is a bit too soft spoken in the role. When he has to talk tough his voice is missing that edge to make it believable. Conversely he is very good at conveying the character's cleverness, such as using the thousand dollar bounty to his advantage.
Peggy Stewart is really good as Kate Wells. She shows a lot of spunk in her character, equally at home shooting it out with the outlaws or sitting behind her counter as postmistress. no one intimidates her, not the Sheriff, not the Judge, not even Boyd. Now that takes guts.