Tom Evans (Jon Dawson), nephew of U.S. Marshal Sandy Hopkins (Raymond Hatton), has just trailed his cattle to Yucca City, where he intends to sell to Ben Crowley (Harry Woods), owner of practically everything in town.Tom loses his money in a crooked game ran by Crowley. "Nevada Jack" McKenzie (Johnny Mack Brown), a U.S. Marshal working undercover, watches the game and secures one of the "fixed" decks of cards. Later, Tom discovers Crowley's men rustling his cattle and is shot. Nevada finds him severely wounded and hides him with Jeff Lewis (Sam Flint) and his daughter Mary (Ellen Hall). Sandy, posing as a dentist, arrives in town after a wire from Nevada. The latter confronts Crowley with the crooked deck and also with the fact that Tom is still alive, and demands a partnership from Crowley. When Crowley learns that Lewis is hiding Tom, he decides to have both Tom and Nevada killed.
Mysterious deaths have been occurring in the same towns as Miller's Circus and the Governor has sent Ken Kenton to investigate. Ken joins the show but when he realizes that Bargoff is involved, Bargoff has fled and taken Mary Hiller as a hostage. The trail leads to Baron Petroff who concocted the deadly chemical and Ken quickly finds himself the Baron's prisoner.
John Mason returns to the Sally Ann mine to claim his half share. Janet Cater also returns although her father lost his half share to Joe Ryan. Ryan and his gang are also there to get the gold. A mysterious Phantom is also present. Mason's plan to expose Ryan as an outlaw and to force him to turn his share to Janet works. But when distracted by the Phantom, John is made a prisoner by the gang.
Ken Maynard's exceptionally intelligent horse, Tarzan the Wonder Horse, is the star of this western about evil cowboy Steve Frazer (Welch) who gathers horses for slaughter, whose meat is sold to pet food manufacturers. The wild horse Tarzan frees the doomed horses from their corrals, and Frazer convinces the Sheriff that Tarzan is a threat and can be shot on sight. Local cowboy Ken Benson (Maynard) and rancher Pat Riley (Kennedy) work together to clear Tarzan's good name and put Frazier behind bars for his evil deeds.
John Drury saves Duke, a wild horse accused of murder, and trains him. When he discovers that the real murderer, a bad guy known as The Hawk, is the town's leading citizen, Drury arrested on a fraudulent charge.
The wall to Surprise Valley has broken, and Jane Withersteen is forced to choose between Lassiter's life and Fay Larkin's marriage to a Mormon.
Luke Hawkins, the jack-of-all-trades of the western town of Lariat, falls in love with Mary Darling, the leading lady in a traveling theatrical troupe (of the old-fashioned "mortgage melodrama" variety). He follows her to New York, takes another series of jobs, and finally works as an extra in Mary's new production. Just as the play is about to flop, Luke recognizes Mary, and his rush to take her in his arms turns the show into a hit.
'Tuck' Martin, a crooked rancher, plots to acquire possession of the neighboring ranch belonging to 'Pop' Melody, whose daughter, Molly, is in love with 'Big Boy.' Bill Lang, the Melody ranchman, is in league with Martin and succeeds in rendering Melody helpless, although he had originally intended to have him killed. An attack on the cottage discloses the double dealing of the foreman, who is finally brought to justice, with nothing but happiness left for 'Big Boy' and Molly.
When a hypnotist named Norman Osgood mesmerizes a man named Harrison Kirke without his consent, Kirke threatens to kill him. Afraid for his life, Osgood hypnotizes another man named George Clayton and tells him he must murder Mr. Kirke one hour before the arrival of the dawn. Kirke is found murdered the next day, and Clayton starts to believe he was the murderer.
Jode MacWilliams, a cowboy working on the Circle O ranch, has a crush on the boss's daughter, Peg. After his friend writes a love letter for him, an Indian steals and delivers it to Peg. Meanwhile, word of Jode's affection reaches Peg's father, who has a decidedly less romantic view of this young couple.
A lost film. As described in a film magazine Exhibitors Herald on March 16, 1918: "a forest ranger known only as Headin' South (Fairbanks) goes forth in search of Spanish Joe (Campeau), a Mexican responsible for most of the treachery and outlawry along the U.S.-Mexican boarder. Headin' South gains quite a reputation as he goes along and finally believes himself worthy of joining Joe's band. in a whirlwind finish in which Joe is captured, Headin' South meets one of Joe's near victims (MacDonald) and falls in love with her."
Two families, abolitionist Northerners the Stonemans and Southern landowners the Camerons, intertwine. When Confederate colonel Ben Cameron is captured in battle, nurse Elsie Stoneman petitions for his pardon. In Reconstruction-era South Carolina, Cameron founds the Ku Klux Klan, battling Elsie's congressman father and his African-American protégé, Silas Lynch.