Sunset of Power is regarded as one of Buck Jones' more meritorious Universal westerns. The heavy of the piece, grim-visaged cattle baron Neil Brannum, drives everyone around him mercilessly, including his own granddaughter Ruth. In retaliation, a caped-and-masked Spanish bandido stages nightly raids on Brannum's spread.
A cowboy captures two rustlers and collects a $5000 reward. Using the money to take a vacation, he winds up getting accused of a murder he didn't commit.
Texas Ranger Ranny Maitland's father is feuding with his neighbor Lockhart. Pretending to be on Lockhart's side in the feud, Ranny goes to investigate. Meanwhile is father is murdered and Lockhart arrested.
It is California in 1852 that only recently being surrendered by Mexico to the United States and admitted into the union. Most of the land-owners of California were the descendants of the Dons who had colonized it a hundred years before and whose title deeds bore the signature and seal of a long-dead Spanish king. But, by a loop-hole in the law, the title-deeds of the Dons could not be recognized, and this opened the door of organized gangs of land-grabbers, such as the one led by Joe Kincaid, to operate with a prime excuse for legitimate plunder and robbery. In most cases the law was unable to cope with the situation. Then Rosita Castro, the daughter of Don Pasqual Castro, masked and disguised as a man, organized a band of vigilantes to fight against the tyranny of the outlaws, aided by an undercover federal agent, Jim Kearney.
Kirk Allenby is hired by the Cattleman's Association to track down and arrest a rancher who they believe is stealing cattle. Allenby finds his quarry but is astounded to discover that that man, Bob Enright, looks enough like him to be his twin. He is forced to shoot Enright, but as the man lay dying he gets Allenby to promise that he will help Enright's sister, who is being forced to marry the real boss of the cattle rustling operation, who has framed Enright in order to take over his ranch.
A miner who was swindled out of his mine by a banker turns to robbing stagecoaches. Several years after he is tracked down and killed, his son comes to town to tangle with the banker.
Manning breaks out of prison and joins Blake's gang of outlaws. Later a paroled Muggs arrives to rejoin the gang. Muggs is the only one who knows where the stolen money is hidden and Manning is after it.
Ken Armstrong (Ken Maynard) finds himself a mine owner and a daddy simultaneously when a friend dies and wills him his mine and his baby. The outlaws eying the mine try to frame the hero for the death.
Jack is looking for the man that was responsible for the death of his sister after he hired her as a school teacher. When he runs into school teacher Ann who was just hired by Corey, he soon realizes Corey is the man he is after. Lacking proof, he works on Corey's nerves hoping to get a confession from him.
A pair of crooked deputies steal a gold shipment, murder a young boy's father and pin the blame on a cowboy. The murdered man's son and his dog set out to prove the cowboy's innocence.
Tom Hilton and Stub Macey are heading to the Jergenson ranch to buy his cattle. But Jeckyl and Sheriff Slater control the cattle market forcing the ranchers to buy at their price and they intend to keep the newcomers out.
Swifty is framed for the murder of Alec MeNiel by the Lawyer Cheevers and the stepson Price. Then they incite the locals to form a lynch mob, but Swifty has an unexpected ally in the Sheriff who knows Price was after his stepfather's land.
Kirk Baxter has been sent to investigate murder and robbery involving gold shipments. Identifying a gang member by his bullets, he uses that man's horse to locate and join the gang. He learns the gang is tipped off to the shipments by a mine employee using carrier pigeons. But the next message reveals his true identity and he is made a prisoner.
Edith overhears Bart's plan to rob the bank so she informs Ken. But she is also overheard and when Ken goes to investigate, Bart's Henchman Prod frames him for the robbery. Thrown in jail, Ken's pal Pedro arrives with a plan to get him out.