When Rocklin arrives in a western town he finds that the rancher who hired him as a foreman has been murdered. He is out to solve the murder and thwart the scheming to take the ranch from its rightful owner.
Questions arise when Senator Stoddard attends the funeral of a local man named Tom Doniphon in a small Western town. Flashing back, we learn Doniphon saved Stoddard, then a lawyer, when he was roughed up by a crew of outlaws terrorizing the town, led by Liberty Valance. As the territory's safety hung in the balance, Doniphon and Stoddard, two of the only people standing up to him, proved to be very important, but different, foes to Valance.
Dan Evans, a small time farmer, is hired to escort Ben Wade, a dangerous outlaw, to Yuma. As Evans and Wade wait for the 3:10 train to Yuma, Wade's gang is racing to free him.
A small-town sheriff in the American West enlists the help of a disabled man, a drunk, and a young gunfighter in his efforts to hold in jail the brother of the local bad guy.
Stodge City is in the grip of the Rumpo Kid and his gang. Mistaken identity again takes a hand as a 'sanitary engineer' named Marshal P. Knutt is mistaken for a law marshal. Being the conscientious sort, Marshal tries to help the town get rid of Rumpo, and a showdown is inevitable. Marshal has two aids—revenge-seeking Annie Oakley and his sanitary expertise.
Union officer Kerry Bradford escapes from a Confederate prison and races to intercept $5 million in gold destined for Confederate coffers. A Confederate sympathizer and a Mexican bandit, each with their own stake in the loot, stand in his way.
The Trail Blazers are bringing in a prisoner to stand trial for bank robbery, when several attempts are made to kill him; convinced of the man's innocence, they arrange a trap for the real thieves.
Two down-on-their-luck former outlaws volunteer to be Texas Rangers and find themselves assigned to bring in an old friend, now a notorious outlaw.
At a desolate relay station in the west, a stagecoach attendant and a stranded woman traveller are held captive by a band of escaped convicts.
A Confederate troop, led by Captain Lafe Barstow, is prowling the far ranges of California and Nevada in a last desperate attempt to build up an army in the West for the faltering Confederacy. Because the patrol saves a stagecoach, with Johanna Carterr as one of the passengers, from an Indian attack, and is marooned on a rocky mountain, it fails in its mission but the honor of the Old South is upheld.
After a stagecoach holdup, Frank Slayton's notorious gang leave Ben Warren for dead and head off with his fiancée. Warren follows, and although none of the townspeople he comes across are prepared to help, he recruits two others who have sworn revenge on the ruthless Slayton.
A bandit disguises himself as an officer in an attempt to woo a saloon singer.
Problems come in the form of one of Hopalong Cassidy's neighbors, but the matter is settled when Hoppy roots out the troublemaker.
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.
Hoppy goes undercover as an outlaw (which permits him, for once, to drink and be mean to children) to track down a bunch of outlaws operating along the border. Loco, the head bad guy, deflects suspicion from himself by pretending to be a moron.
Finishing a trail drive, Hoppy and the boys head to town and immediately get caught up in the conflict between school teacher Miss Abott and next door saloon owner Mawson. When Miss Abott disappears, Hoppy gets a clue to her location and rescues her from Mawson's cabin. It looks like Mawson is the man he wants, but Hoppy finds an item that indicates otherwise.
Sue Morgan gets Hoppy and his friends to join their expedition looking for Indian artifacts. Expedition leader Atwood makes a deal with nearby cattle rustler Morgan to loot the Indian treasures instead and sell them. Hoppy is on to their plan and pretending to leave follows them. Not only is he outnumbered by Morgan's men, but California has himself about to be sacrificed in an Indian ritual.
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.
Joe Weller has instigated a conflict over water rights between two ranchers. The idea is to have the ranchers do each other in then move in and take over. Hoppy and the good guys won't let this happen.
As rustled cattle have mysteriously disappeared, Johnny sends for his friend Hoppy, Hoppy arrives and immediately suspects Dan Slack. Realizing his telegram about Slack was intercepted, he locks up the operator Lafe knowing he can escape. Tailing Lafe he finds a secret entrance to a mine and inside finds the missing cattle. But Slack's men also find him just as the cattle are stampeded through the mine shaft.