Traveling north into Arizona, Cisco finds that someone committing robberies has been impersonating him and he is a wanted man. After retrieving some of the stolen loot, he is caught with it in his posession and put in the guard house. A friend whose life he recently saved beaks him out and Cisco heads out to find the impersonator and clear himself.
A gang of criminals, which includes a piano player and an imposing former convict known as 'Gruesome', has found out about a scientist's secret formula for a gas that temporarily paralyzes anyone who breathes it. When Gruesome accidentally inhales some of the gas and passes out, the police think he is dead and take him to the morgue, where he later revives and escapes. This puzzling incident attracts the interest of Dick Tracy, and when the criminals later use the gas to rob a bank, Tracy realizes that he must devote his entire attention to stopping them.
Gridley is mining silver from an old Mexican mine and bringing it into the USA thru a passage into his worthless mine. Border guard Rogers suspects Gridley and finally finds the secret entrance to the Mexican mine. He sends Lee Madison for help only to have her captured by Gridley. Trigger brings help that takes care of Gridley's men and now Roy has to rescue Madison.
Two ex-soldiers return from overseas--one of them having smuggled into the country a French orphan girl he has become attached to. They wind up running into their old sergeant--who hates them--and getting involved with a race-car builder who's trying to find backers for a new midget racer he's building.
Knowing the railroad is coming, Carter is after the rancher's land. Bob and Chito return just in time to save Banker Stockton and his money from Carter's men. When Stockton then lends the ranchers money, Carter has them burned out. Bob knows Carter is responsible and when Carter's henchman Saunders is recognized, Bob goes into action.
Notorious shootist and womanizer Quirt Evans' horse collapses as he passes a Quaker family's home. Quirt has been wounded, and the kindly family takes him in to nurse him back to health against the advice of others. The handsome Evans quickly attracts the affections of their beautiful daughter, Penelope. He develops an affection for the family and their faith, but his troubled past follows him.
To get the Delaney ranch Cole's henchman Anders has started a phony range war between the cattlemen and sheepmen. After killing Delaney, he tries to kill his daughter Jill and then Roy who was sent to investigate the war. But the failed attempts gives Roy the information he needs.
Buster Crabbe and Johnny Weissmuller battle it out in Cajun country! Johnny, a riverboat pilot on the Mississippi, is seduced away from his fiance (Carol Thurston) by a rich outsider (Virginia Grey) who's nursed him back to health after a serious accident. She owns a large piece of the swamp and has outlawed hunting on her property. His rival Mike (Crabbe) is a trapper who harbors deep resentment for Johnny and his new wealthy friends. When he feels Johnny is responsible for the hunting ban, he resorts to destructive acts of vengeance.
Rodeo star Roy Rogers returns home to find that his old friend Tom Craig has been murdered after he was accused of stealing a family crest from Helen Williams. Helen joins up with Roy and Gabby Whittaker to find the killers and the crest.
Gabby doesn't want to breed his horse the Golden Sovereign with Roy's. When Sovereign and Roy's horse escape, the Sovereign gets shot accidentally by Skoville but Roy is blamed and jailed. A year later Roy returns with Trigger, the son of the Sovereign. When Skoville reveals he was present when the horse was shot, Roy sees an opportunity to clear his name.
A young outlaw gets involved with a gang of crooks. When he tells them he is breaking away, they threaten to pin a false murder charge on him. But he is rescued and reformed by his sister, and an undercover agent for the express company.
During World War II, a young boy and girl, living with their respective families in an apartment house that had restrictions against pets, adopt a lost dog and hide it in a vacant apartment, which may have been the only vacant apartment in the United States at the time this movie was being filmed. A burglar breaks in and the apartment is damaged when the dog and crook have a tussle. This blows the dog's cover, but the kids enlist him in the K-9 Corps, and the dog distinguishes himself in the WWII Italian campaign
After some gun play with a posse, the James Gang head for Quinto in a section of land which is not a part of America. Anyone there is beyond the law so the town is populated with outlaws. Next to arrive is Sheriff Rowley, following his brother whom the Gang have brought in injured. Rowley has no authority and gets on well enough with the James boys but is soon involved in other local goings-on, including a move to vote for annexation with Oklahoma which would allow the law well and truly in.
Roy Rogers rides to the rescue when a bank robber's orphaned son (Tommy Cook), who is living at a ranch for homeless boys run by Gabby Whittaker (George "Gabby" Hayes), attracts the attention his father's rowdy gang, who want to claim the boy's inheritance for themselves
Dick is faced with a series of brutal murders in which the victims, all from different social and economic backgrounds, are viciously slashed to pieces. Suspects abound but Tracy, getting a clue that there will be 15 murders in all, must find the common thread among the victims before more are killed.