Ken Williams pursues a masked, mysterious villain known as "The Rattler," who terrorizes those involved in the building of a tunnel.
Chapter One: "The Rattler"
Ken Williams and Corwin Transportation Company are attacked by a mysterious man known as "The Rattler." Ken pursues The Rattler's men on his horse, Tarzan.
Chapter Two: "The Man Nobody Knows"
After a coach crash, Ken continues to track The Rattler, who has kidnapped his friend Breezy. Realizing that the kidnapping is a trick, Ken races after The Rattler, but is caught in a dynamite explosion.
Chapter Three: "The Eye That Never Sleeps"
Ken suspects Dr. Edwards of being The Rattler. Breezy attempts to photograph The Rattler. When he pursues a band of riders, Ken is led into an ambush.
Chapter Four: "The Human Target"
Ken and Breezy head to town to have Breezy's photos developed. On the way, Ken finds The Rattler's disguise hidden among some rocks, puts it on, and pretends to be the villain, eventually getting trapped by the real Rattler.
Chapter Five: "Phantom Outlaws"
About to be used as "target practice" by The Rattler's men, Ken is saved by Breezy. They catch up to The Ratter, tell him to unmask, and find out it is a friend, Henderson, who has also found a disguise. They all get trapped in a secret cave.
Chapter Six: "The Perfect Crime"
Henderson is about to reveal the identity of The Rattler when he is killed by a dart. On the pursuit of the killer, Ken and a wagon train are lead into an ambush. One of the leaders of the train (Gene Autry) fires at Ken to get even.
Chapter Seven: "Tarzan the Cunning"
Breezy alerts everyone that The Rattler is posing as Ken. The real Ken is taken prisoner and escapes, only to be caught in gunfire by The Rattler.
Chapter Eight: "The Enemy's Stronghold"
Breezy finds The Rattler's closet full of disguises, while the villain poses as yet another person. Ken and Breezy pursue The Rattler to his den.
Chapter Nine: "The Fatal Warning"
The Rattler pursues Ken and Breezy, locking them in his disguise room. He kidnaps their friend, Jane.
Chapter Ten: "The Secret of the Mountain"
Ken once again dresses as The Rattler to trap the criminal and save Jane. They are caught in a fight that involves deadly gas and are sent to the hospital.
Chapter Eleven: "Behind the Mask"
Ken continues to pursue The Rattler and unmasks him, with the help of Tarzan, just before he is kicked over a cliff.
Chapter Twelve: "The Judgment of Tarzan"
Tarzan saves Ken from falling over the cliff, and Dr. Edwards is revealed to be The Rattler, but the doctor is only another of the villain's disguises. Ken sets a trap where all of the suspects show up. The evil Frank Blayden is exposed as The Rattler and dies in a mine explosion.
|Ken Williams||Ken Maynard|
|Jane Corwin||Verna Hillie|
|Breezy Baker||Syd Saylor|
|Frank Blayden||Edward Earle|
|Dr. Edwards||Hooper Atchley|
|Wagon Driver||Smiley Burnette*|
|* Not Credited Onscreen|
|Produced by||Nat Levine|
|Directed by||Otto Brower and Breezy Eason|
|Supervised by||Victor Zobel - Armand Schaefer|
|Story by||Sherman Lowe – Barney Sarecky – Breezy Eason|
|Continuity by||Ben Cohen – Armand Schaefer|
|Photography||Ernest Williams – William Nobles|
|Edited by||Earl Turner|
|Sound Engineer||Terry Kellum|