At the beginning of the 1913 Mexican Revolution, greedy bandit Juan Miranda and idealist John H. Mallory, an Irish Republican Army explosives expert on the lam from the British, fall in with a band of revolutionaries plotting to strike a national bank. When it turns out that the government has been using the bank as a hiding place for illegally detained political prisoners -- who are freed by the blast -- Miranda becomes a revolutionary hero against his will.

At the height of the frontier era, a train races through the Rocky Mountains on a classified mission to a remote army post. But one by one the passengers are being murdered, and their only hope is the mysterious John Deakin, who's being transported to face trial for murder.

Ed Ryan is a Texas ranger who goes undercover to trap a criminal gang headed by Luke Andrews. Posing as the wanted killer Robert Larkin, Ed is able to move freely amongst the town riffraff. Marshal Bullock learns that the brains behind the gang of Luke Andrews is a group of supposed respectable businessmen.

Years ago, the young Five Fingers fought for the rural town of Marseilles against brutal police oppression. Now, after fleeing in disgrace, Tau, one of them, returns to Marseilles, seeking only a peaceful life. When he finds the town under new threat, he must reluctantly fight to free it.

A young doctor rejects his older outlaw brother Johnny who put him through medical school by dubious means. The brothers find themselves on opposite sides of a range war between homesteaders and a crooked cattleman.

During a shootout in a saloon, Sheriff Hunt injures a suspicious stranger. The doctor's assistant, wife of the local foreman, tends to him in prison. That night, the town is attacked and they both disappear—only the arrow of a cannibal tribe is found. Hunt and a few of his men go in search of the prisoner and the foreman's wife.

Molly, the shy, romance-starved wife of an arrogant frontier sheriff, finds herself drawn to a prisoner in her husband's jail. This prisoner, a handsome young man named Johnny, plays on Molly's sympathy and convinces her to help him escape. Molly then accompanies Johnny on his cross-country flight but soon learns he's simply been using her. Molly makes the best of the situation, however, and by the time the sheriff's posse catches up with them, Molly shows that she's learned how to assert herself.

It is now an accepted fact that the best of Johnny Mack Brown's Universal westerns were directed by the talented Joseph H. Lewis. Boss of Hangtown Mesa may not be in the same league as the Brown-Lewis classic Arizona Cyclone, but it comes awfully close. This time around, hero Steve Collins (Brown) comes to the aid of Betty Wilkins (Helen Deverell), who has taken over the telegraph-line business established by her uncle John (Henry Hall). The latter was murdered by outlaws who don't cotton to having the territory linked up electronically with the rest of the world.

Wealthy rancher Bick Benedict and dirt-poor cowboy Jett Rink both woo Leslie Lynnton, a beautiful young woman from Maryland who is new to Texas. She marries Benedict, but she is shocked by the racial bigotry of the White Texans against the local people of Mexican descent. Rink discovers oil on a small plot of land, and while he uses his vast, new wealth to buy all the land surrounding the Benedict ranch, the Benedict's disagreement over prejudice fuels conflict that runs across generations.

Marshall Jed Cooper survives a hanging, vowing revenge on the lynch mob that left him dangling. To carry out his oath for vengeance, he returns to his former job as a lawman. Before long, he's caught up with the nine men on his hit list and starts dispensing his own brand of Wild West justice.

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.

Two deputies go undercover to save a scientist from his evil kidnappers.