When John Cannon feeds hungry Apache children orphaned by Pima Indian attacks, his ranch is threatened by the two tribes. Buck and Billy Blue find the young Apaches in the desert including Choddi, grandson of Geronimo. Geronimo and his braves come for the children, but the young Apaches mistake them for Pimas and hide in the desert. The Apaches threaten revenge if they are not returned, while Pimas wait nearby endangering the children.

Ranch foreman Sam Butler returns to his native border town to avenge the death of his daughter. Sam, raised by his adopted father Ben Lynch, learns his daughter has been killed by Lynch's would be gunfighter son, Tom. Reunited with his Mexican wife Trinidad, Sam refuses all advice and vows to kill the boy. John Cannon leads the ranch hands to the border city in an attempt to stop the shoot-out.

""A factual drama based on the 10th Cavalry, a Negro regiment formed in 1866. Lawlessness in Tucson brings martial law--and the 10th--into open conflict with the town's white populace and an army of outlaws. Members of the honorary 10th Cavalry, formed in Los Angeles in 1966, are featured in this episode."" (TV Guide)

Billy Blue Cannon faces possible hanging when he is court-martialed on the charge of killing an army general's son. Billy Blue saves an Indian girl from advances by a drunken army lieutenant, who is killed in the fight. When the girl flees to the Apache stronghold, Buck and Manolito risk their lives to persuade Cochise to release Blue's only eyewitness. Her testimony is discarded when the court learns her release was obtained by a bribe. It becomes obvious to John Cannon that the court-appointed defense is incapable of saving Billy Blue, and John personally takes over his son's defense

Buck and Manolito invade the Apache stronghold to rescuer a captive white girl. Ann, an Apache slave for five years, is rescued by Buck and Manolito as she flees from her captors, but her frail sister Olive is recaptured. John asks a passing Army detachment for aid, but the unit is massacred before it can help. Buck and Manolito ride unarmed into the Apache stronghold prepared to buy the girl's freedom, but the Apache chief and the medicine man offer to let them go free with the girl if Manolito can survive a test of courage.

A gunfighter attempts to goad Blue into a shootout. Participating in his first trails-end celebration that traditionally follows a grueling cattle drive, Blue joins his father John Cannon, Uncle Buck and Manolito and the town's other weary but happy cowhands in observing the occasion. A barroom argument develops between Blue and short-tempered Johnny Keough, who invites young Blue outside to settle the matter with their guns. Well aware of the obvious advantage the well-known gunman Keough has over him but also concerned about his own pride as a result of being publicly challenged, Blue finds himself facing one of the most important decisions of his life.

A former prison doctor accused of malpractice becomes the only man to whom John Cannon can appeal in efforts to save the life of his seriously ill wife. Lawman Tad Garnet requests a night's lodging at the Cannon ranch while escorting Mathew Kendel, a one-time prison physician, to jail on charges of willfully causing the deaths of many of his convict patients. When Victoria suddenly falls ill and needs an operation to save her life, John must ask the now-embittered Kendel for help.

Buck Cannon jeopardizes his life, when he tries to turn two Apaches into wranglers. Sourdough and Saddleblanket quickly become valuable hands. When an Apache war party kills three ranchers and kidnaps the two Indian wranglers, all but Buck believes the two Apaches are killers and have reverted to their old ways. The High Chaparral group tracks the war party to an Army fort the Indians have captured and where Buck lies seriously wounded beyond reach of his comrades. Almost dying of thirst, Buck's only chance for survival lies in an appeal to his Indian wranglers inside the fort to turn on their fellow Apaches.

An Indian outbreak threatens to erupt when Billy Blue Cannon and an Apache boy fight over a wild horse. Chatto, son of an Apache chief, first discovers the prized stallion, but fails in his attempt to capture it. When Billy Blue successfully ropes the horse, Chatto becomes infuriated with Cannon and steals it back. Billy Blue retaliates and a feud begins. Chief Natchez approaches John Cannon and warns him of trouble if Chatto loses the horse. The two boys meet and fight while High Chaparral wranglers and Apache braves watch and prepare for battle.

Lucien Charot raises his freight prices by having Indian attacks faked against his wagons. John interests an El Paso stage and freight line in extending operations to Tucson with local merchants financing the plan. Charot increases the phony raids and the frightened merchants withdraw from the deal. John then puts his ranch up to guarantee the initial safety of the new line. Victoria joins John for the first ride into Tucson while Charot and his gunmen wait in ambush.

After accidentally uncovering a silver deposit, an excited Buck Cannon wastes no time in talking Manolito into joining him in a major real estate investment. Unable to raise the down payment to Jeff Patterson, who has agreed to sell his ranch, Buck invites Manolito to be his financial backer for half-interest. After Victoria has turned over a priceless necklace to her brother for collateral on a loan, the new land owners learn hat their silver cache is worthless.

Billy Blue is captured by the Apaches, who use him as a pawn in a bartering game to stave off an impending cavalry attack. Although he denies pillaging an army weapons patrol, Apache Chief Morales anticipates a retaliatory attack by the cavalry and threatens the life of his hostage, Blue, unless his terms are met. John Cannon, who believes the Indians to be innocent of the pillaging charge, pleads for time, and vows to bring in the guilty parties in a desperate attempt to save his son.

Determined to seek a new career as an artist, Blue announces his decision to leave the Cannon Ranch for good. Blue is chided by men of the Chaparral for assuming his drawings have merit. Blue has the last work, however, when an editor sees some of his work and offers him a high-paying job in the city.

John Cannon's first wife is killed during an Apache raid. Buck, his brother, can't stop Mexican bandits from rustling cattle. Unable to fight on two fronts -- against Mexican marauders and the Indians -- John arranges a defense agreement with his neighbor in Mexico, Don Sebastian Montoya. The Mexican insists that John seal the agreement by marrying Victoria, his daughter, thus solidifying an alliance against the Apache. Moreover, Don Sebastian demands that Victoria's carefree brother, Manolito, come along to guarantee her safety.

Buck, Manolito and Billy Blue are sent to Tucson for food, supplies and boots, but are sidetracked instead by women and song. While John Cannon awaits his trio's return with the goods, Buck promptly enters a poker game with cowhand Kansas and loses the supply money, Manolito courts Pearlita who rolls him for his money, and Billy Blue sets out with little Rag-Tag Tina to buy the fanciest pair of boots in Tucson. Problems grow when the boys try to help Fergus MacLeish and his wife from being held up, only to lose the guns they need in Tucson.

The future of the ranch is jeopardized when bandits steal a prize bull and breeding stock which Billy Blue Cannon and Manolito Montoya have bought in Mexico with the last of the Cannon money. Victoria persuades husband John Cannon to send the boys to her father's rancho for the cattle after his brother Buck Cannon is injured. Manolito bargains with his father, Don Sebastian Montoya, for his second best bull. Don Sebastian thinks the boys are pulling a prank and hires bandits to steal the bull. They boys make a desperate attempt to catch the thieves and still prove their trustworthiness.

John Cannon needs cattle from Mexican ranchers for his Army beef contract, but finds the frightened men are being forced to sell at cheap prices to a ruthless cattle buyer. When John offers them higher prices, the ranchers refuse to sell because Dolf Tanner has threatened to kill them if they do. John and brother Buck try to force the ranchers to sell by refusing them watering rights, as they drive their herds toward Tanner. But Tanner strikes back by giving Apaches new rifles and urging them to kill the Cannon herds.

When Billy Blue Cannon is forced into a showdown with wanted gunfighters, he is saved by a wandering dentist who proves to be fast with a gun. John Cannon returns the favor to Doc Henry by agreeing to send Billy Blue to help the dentist establish a practice in Tucson. Billy Blue is kidnapped en route and held for ransom by the gunfighters, Jacques Dubois and Kid Curry. The boy loses faith in his new friend when the dentist throws in with the crooks. John Cannon corners Doc Henry with the ransom and prepares for a shoot-out.

Buck Cannon goes to work as foreman for a lovely neighboring widow, and clashes with his brother John when the job appears permanent. Buck falls in love with the widow, Melanie Cawthorne, and becomes her tool as she strives for quick riches and respectability. As water grows scarce, she buys stolen Mexican cattle from Romero without Buck's knowledge.

John Cannon and Billy Blue are captured by Apaches far from home and made to face death from lack of water. John and Billy force a wounded Indian, Klosen, to lead them toward water but the Apache escapes. Buck and Manolito catch a glimpse of a war party wearing John's and Billy's hats but harsh desert winds make it impossible to track the missing pair. When John and Billy do find water, renegade Chief Soldado ties them to a rock to die of thirst.

The Cannons care for a wounded relative who repays them by stealing the ranch payroll. Uncle Dan Brookes arrives suddenly after a 15-year absence seeking safety in the heavily fortified ranch. He conceals the fact he is wanted dead or alive for murder and has been shot by bounty hunters Mace and Gurney. When Buck hires the bounty hunters as ranch hands, Brookes saves his own skin by offering to help Mace and Gurney steal the Cannon payroll.

A bounty on Apache scalps disrupts peace between the Cannons and the Indians. When Apache raids close Judah Austin's mine, he offers Stoner a bounty for Indian scalps despite John Cannon's objections. Stoner's son Chad is wounded in an attack on the Apaches and turns against his father while recuperating at the High Chaparral ranch.

An Army deserter accused of murder takes Billy Blue as hostage. Graham Jessup enlists Billy Blue to help him escape by fabricating a story that he has been mistreated because he is a Negro. Jessup makes Billy his prisoner when the young man hesitates to lead him into forbidden Apache land. The pair are cornered in the forbidden land by a large band of Indians, complicating the rescue efforts of John Cannon, Buck and the cavalry.

The celebration of a peace treaty with the Indians is cut short for the Cannons by scalp hunters disguised as lawmen. Nickanora, an old friend of Manolito and Victoria, admits he has come from Mexico with Johnny Ringo's gang to scalp Indians for profit. When the gang kills an Indian family, Mano goes after the group alone and is captured. John Cannon and the High Chaparral wranglers locate Manolito, but hesitate to start a gun fight, fearing an approaching Apache war party will be alerted by the shots.

Don Sebastian, wounded by a would-be assassin, plays on the sympathy of his family and friends in a scheme to gain control of the Cannon Ranch. On his pretended death bed, Don Sebastian extracts a promise from Manolito to marry Anita Santiago, a beautiful but headstrong neighbor in a plot to join the two ranchos. Victoria gives in to her father's wish to persuade John to sign the Cannon Ranch over to Manolito. Don Sebastian's plan begins to falter when Mano learns that his father is faking, and the assassin returns for a second attempt on Don Sebastian's life.