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.

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.

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.

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.

An Apache renegade and his followers plan to kill Cochise's peace representative in the Cannon ranch house and start a new Indian war. Medicine man Nock-Ay-Del explains that Cochise will agree to live peacefully if John Cannon offers sufficient gifts. Buck warns against a death trap when an outpost guard is killed during negotiations. Sub-chief Soldado and three warriors move in towards the ranch house to accomplish their purpose.

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.

Billy Blue Cannon quits the ranch after a quarrel with his father and leads a peace representative of the President to Cochise. On the trail Blue falls in love with Kelly's adopted Apache daughter, Moonfire. Kelly, an idealistic dreamer, meets Cochise's demands for a strip of land separating the High Chaparral from Tucson. This would cut the Cannons' supply route and threaten them with bankruptcy. John, angered by the peace terms and his son's choice of a wife, prepares to defend the ranch against the Apaches.

Billy is taken hostage by Apaches after he ignores Buck's advice and frees a white girl from them. Buck learns Apache leader Santos considers himself to be Sarah's husband. Buck hesitates to use force which would break the Cannon peace treaty with the Indians. Santos threatens Billy's life unless Sarah is returned.

Gilbert Roland guest stars as the surprise heir to the Montoya ranch in this special two-hour presentation. The sudden, peaceful passing of Don Sebastian Montoya brings his daughter Victoria, his son Manolito, John Cannon and Buck to the Montoya ranch to attend funeral services and to settle estate matters. All are amazed to learn the will leaves the vast Montoya holding to Don Sebastian's ne'er-do-well brother Don Domingo, a charming, irresponsible rascal currently living in Mexico City. Upon his return to the family home to claim his legacy, Domingo shocks the family by announcing he plans to sell the ranch and travel. A series of unexplained raids on his new-found cattle and property serves to uncover a little-known dimension of Don Domingo

This pilot launches the saga of the Cannon family as they fight to establish a ranch in the Arizona territory of the 1870s. Marauding Apaches led by Cochise are on the warpath. The Army orders the Cannon family to move on, but Big John Cannon won't budge. While his brother Buck rides off to recruit gun-carrying cowhands, Big John learns of another enemy: a Mexican land baron claims the Cannon property, and dispatches his men to seize the cattle.