Money is mysteriously disappearing from a locked trunk atop the stage even though the trunk arrives still locked. When pals Bob Rivers and Grizzly get the jop driving the stage, the same thing happens.
A cowboy on the run from a posse finds the clothes and ID of a preacher on the trail. He assumes the man's identity, but when he arrives at the nearest town, he rides into the middle of a hanging--and the man who is being hanged knows his real identity.
Leaving town with the Sheriff after him, Tex joins up with the Trouble Busters Skinny and Windy. In Placerville he runs into trouble with Bill Jarvis leading to a mad rush to file on oil rich land.
The Hawk has broken out of prison and the Sheriff and Sorrenson have a plan to have Whitlock pose as the Hawk, infiltrate the gang, and recover the stolen bonds. All goes well until The Chief who knows the real Hawk arrives.
Reporter Speed Morgan helps Flash Barrett escape from the police and this gets him into Flash's gang where he poses as a gangster. Flash and his gang head west guning for Bill Miller who failed to send some diamonds on to Flash. Speed hopes to bring Flash to justice but is in trouble when his true identity is revealed.
After Burton kills Dad Mason and makes it look like a suicide, Ace Cooper arrives to investigate. He poses as a coward during the day but at night he becomes the daring Dude Bandit.
Skinner and his gang are grabbing land from the ranchers. When they go after Kerry's ranch Ken stops them. Skinner frames Ken for rustling but the Sheriff is on Ken's side, and with the help of his brother Earl's Boy Scout troup they go after the gang.
The Llano Kid is robbing stages but only taking money from Montana Slade's Cottonwood Mine. He then gives the money to those cheated by Slade. The Sheriff is after him and eventually obtains a picture and displays wanted posters and is soon after him.
Montana and sidekick Pancho hire on at the Lopez rancho to fight Daggett and his outlaw gang. But Lopez's foreman Barnes is one of Daggett's men and he frames Montana for murder.
Kincade and Blake cause a mail plane carrying a payroll to make a forced landing in the desert. When they try to get the money, prospectors Ted and Si drive them away. With the pilot shot, Ted takes over as pilot figuring another attempt will be made and this time the Sheriff will be there.
While the original title, "Trailing the Killer" isn't a misnomer, it was a bit misleading since the "trailer" is a dog named Caesar (Caesar the Dog) and the killer is a mountain lion. But the makers also pointed out that Caesar "is the most intelligent dog actor since Rin-Tin-Tin" which probably lured a few Rin-Tin-Tin fans with a show-me attitude. Caesar prowls around the woods of the Northwest, dispatches a rattlesnake, visits his she-wolf mate and their pups, pauses to watch the dainty habits of a raccoon personally washing every morsel of food before eating it---and that raccoon had enough food to use up several minutes of running time---and then saves sheepherder Pierre (Francis McDonald)) from getting eaten by one mean mountain lion. Rin-Tin-Tin he ain't, but then who was?
Ken not only has to fight with his brother Wally over the girls, he has to try and stop the conflict between the cattlemen and the sheepmen. It gets worse when Butch kills Judy's father.
A con man posing as a lawyer tries to sell copies of a phony law book. Things get serious when he has to defend a young man falsely accused of robbery.
Cowboy is hired by an archaeologist to help find "Hidden Valley", where an Indian gold treasure is supposed to be buried. Just when he finds it, the archaeologist is killed, and the cowboy his charged with his murder.