Easterner Madeline Hammond buys a ranch not knowing Hayworth is using it to smuggle ammunition across the border. When trouble starts, she brings back Gene Stewart ex-foreman who left the country after fighting with the Sheriff.
Hoppy and new sidekick California Carlson head to California to help out Lucky Jenkins.
Stephen Westcott and Ed Martin scheme to put Jane Travers' wagon line out of business. They want to use it take over all the wagon- train traffic going west. Hoppy, California and Lucky must make sure that doesn't happen.
Posing as a cattle buyer, Hoppy crosses over into Oklahoma where the Jordan brother's and their outlaw gang operate outside the law. After receiving an unfriendly reception when he finds them, he, California, and Johnny rustle their cattle and drive across the river into Texas. He hopes they will cross over to retrieve their cattle and then he can arrest them.
Hoppy goes to town to help Marshal Windy with some rustlers and winds up helping the widow Joyce when confidence men try to take her herd. King's Men songs include: "Hi Thar Stranger" and "Lazy Rolls the Rio Grande."
Escaped criminal "The Fox" hates Hoppy and a Rurales colonel for imprisoning him and lures Cassidy to Mexico in order to exact his vengeance.
Hoppy and Lucky are headed to South America to deliver a heard of cattle. Bay guy Ralph Merritt gets in their way. For a while.
U.S. Marshal Hopalong Cassidy is called when a town becomes overun with bad guys. Disguised as a member of a medicine show, Hoppy discovers that the ringleader is none other than sweet li'l ol' Ma Burton.
Originally written as a stage vehicle for corpulent character actor Macklyn Arbuckle, Ernest Day's The Roundup was first filmed in 1920 with Fatty Arbuckle (no relation) in the lead. By the time the film was remade in 1941, Arbuckle's character, a roly-poly frontier sheriff named Slim (!), was refashioned as a supporting role, with Jack Benny's radio announcer Don Wilson essaying the part. The plot, however, remained fairly intact: Upon hearing that her fiance Greg (Preston Foster) has been killed, Janet (Patricia Morison) agrees to marry rancher Steve (Richard Dix) on the rebound. On the day of the wedding, who should show up but Greg, determined to raise as much Hell as humanly possible
Hoppy, Johnny and Windy are fighting a malicious gang trying to stop a cattle drive from reaching a drought-stricken North.
Richard Dix stars as Dave Morrell, the new marshal of Goliath, Oklahoma. Immediately upon arrival, Morrell finds himself at odds with banker Coy Barrett (Victor Jory), who is actually the leader of all local criminal activities.
Cowboy Ross McEwen arrives in town. He asks the banker for a loan of $2000. When the banker asks about securing a loan that large, McEwen shows him his six-gun collateral. The banker hands over the money in exchange for an I.O.U., signed "Jefferson Davis". McEwen rides out of town and catches a train, but not before being bitten by a rattler. On the train, a nurse, Miss Hollister, tends to his wound. A posse searches the train, but McEwen manages to escape notice. However a mysterious Mexican has taken note of the cowboy, and that loudmouthed brat is still nosing around. Who will be the first to claim the reward for the robber's capture?
On a cattle drive Hoppy, camp cook Windy, companion Lucky, and young Artie Peters encounter an eccentric professor. The professor professes to be searching for the evolutionary missing link, but in reality he is a cattle rustler who uses his dynamite to scatter the cattle in order capture some of them. Hoppy and Bar 20 guys ultimately capture the professor.
Ben Wade and his partner Frosty return to Bellounds' ranch where twenty years earlier Wade was wanted for murder. Unrecognized, he gets a job on the ranch and soon becomes involved in Folsom's cattle rustling and a chance to settle an old score.
Cattle rustler Nevada dreams of living like an emperor in the West. Hoppy and the Bar 20 boys aim to put an end to his dream.
A town bedeviled with outlaws sends for Hoppy, Lucky and California after their own vigilante committee fails to solve the towns problems. Hoppy discovers that the bad guys are led by the town boss, and so are the vigilantes.
The U.S. Army needs more horses for the Spanish-American War. Hoppy must turn his Bar 20 cowhands into Rough Riders to gather up the horses, and of course bad guys try to sabotage the operation.
Burton is after Clark's ranch. He gets the banker to refuse to renew Clark's note and then sends his men to rustle his cattle. Hoppy is Clark's new foreman and is on to Burton's scheme. But just as he learns of the rustling and is about to go after the gang, the Sheriff arrives and arrests him for hiding Johnny who has been accused of robbery.
Hoppy goes undercover as a gambler from the East when Bar 20 cattle are stolen by unknown rustlers. Brennan/Talbot are twin brothers (one a casino owner, the other a rancher) and Hoppy believes they provide alibis for each other while one is out committing crimes. Hoppy gets a job in the casino to learn more but is exposed when a gambling gunslinger notices him.
Before he was killed by Mark Foster's men, Bud Lawton willed part ownership in his ranch to Hoppy and his two pals. When the three arrive they find a fake posing as Lawton. When they expose the imposter, Foster gets the Sheriff to jail them for Lawton's murder.
