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.

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)

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.

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.

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.

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.

Victoria reopens Tucson's only school and befriends a troubled Mexican boy, but is kidnapped by the boy's father. Alberto Ruis, wanted in a slaying, abandons his son Carlos to flee a posse. Carlos remembers his father's promise to return, agrees to live with a local family and attend Victoria's school. He reacts quickly to her affection, but class bullies taunt the boy until he rides to rejoin his father. Victoria and Pedro locate Carlos with his father, Alberto, but Alberto kidnaps Victoria for ransom.

Mexican bandit El Lobo breaks jail and plots to plunder the Cannon Ranch supplies to avenge his imprisonment by Manolito. When heavy rain prevents wagons from reaching the ranch with needed supplies, Buck, Billy Blue, and Manolito attempt to get a mule train through. El Lobo traps the group in an isolated canyon.

Don Sebastian Montoya repudiates his promise to sell a small village on his land to tenants after Vaquero obtains the purchase money. Vaquero received the money from a dying friend to buy the village. This matter becomes complicated when he learns the money may have been stolen by his friend and bandit, Miguel Morales.

Chio, an Apache half-breed and his renegades, capture Cannon's supply wagons. Just as food and ammunition for High Chaparral runs out, Chio is captured and brought to the ranch. Meanwhile, Manolito discovers Tina Granger near a burned out stage coach in an apparently unrelated incident. Tina, Chio's daughter, helps him to escape, but leaves her father when he vows to plunder the ranch to gain recognition. Feeling a loyalty to the Cannons who treated her well at the High Chaparral, she leads Buck and Manolito to the stolen supplies and joins them in a dash for the ranch pursued by Chio and his men.

John Cannon quarrels with a neighbor and Indians, and interrupts Thanksgiving plans. Victoria persuades John to buy the last turkey from argumentative neighbor Fergus McLeish. The deal fails when McLeish, a squatter, insists on a free deed to some Cannon land. Chief Koso steals McLeish's bird, and ranch hand Pedro swaps the Indian a rifle for the turkey. The Thanksgiving dinner is threatened when Chief Koso wants the turkey back and McLeish thinks John is the thief.

A flamboyant Irishman cons Buck into buying a camel, promising it will revolutionize the cattle industry. Cavalry trooper Flanagan misinterprets an order to ""shoe"" his camel Tillie as ""shoot"" and deserts his unit to save the camel's life. Flanagan wears out his welcome at the Cannon Ranch when he cheats at poker, steals Manolito's girl, Pearlita, and admits Tillie can't herd cattle. When Flanagan attempts to escape the Cannon Ranch with Tillie and rejoin the cavalry, he discovers the unit is surrounded by Indians.

Buck hires saddle tramp Orville Kilroy, who hides his criminal past and quickly becomes the most popular hand on the Cannon Ranch. Blue admires Kilroy's ability with a gun, the bunkhouse gang respects him as a top hand, and John Cannon is fascinated with his chess game. Telford Burris and his two sons trail Kilroy to Tucson and accuse him of running out with the money from a robbery. When the Burrises corner Kilroy, Buck must help the new hand to keep Blue's idol from crumbling, or turn the thieves over to the law.

John Cannon is accused of killing the daughter of a Mexican sheepherder and is condemned to death unless steep ransom is paid. Escaped convicts Mitch, Cable, and Kolos accidentally kill the girl while heading for Tucson to reclaim stolen money. They escape the sheepherders by forcing John to change into the prison clothing of the inarticulate Kolos. John is captured and condemned to death, but Manolito promises money for John's release. Buck and Billy Blue fail to raise the ransom

A dishonest Indian agent jeopardizes the future of an Apache reservation started by John Cannon. Capt. Albert Surtee threats the hungry reservation Indians harshly. John takes the law into his own hands and fires Surtee. He suspects Surtee has hired renegade Chief Cubero to start trouble and to steal government cattle. John and Billy Blue attempt to prove John's suspicions by exposing themselves to attack by Surtee and renegade Indians.

Buck tries to find and return the missing husband of Ann Simmons, an old girlfriend. Ann gives Buck a valuable diamond ring to identify him as her representative if he finds her husband Jack. Buck is overpowered by the Truscott gang in a border town. Simmons rescues Buck and the diamond, but refuses to return to his wife. Buck is recaptured on the way home by the thieves and his chances for survival appear slim.

Buck Cannon's plans to open a saloon are threatened by a temperance group led by spirited Frances O'Tolle. Oscar Hipple sells his saloon to Buck, but conceals the fact it was wrecked by Miss O'Tolle's crusaders. Buck hires Warren Case to help restore the saloon and learns Miss O'Tolle started the crusade when she came West to marry Case, but found him drunk. She leads a second assault and Buck's deputized customers jail her for trespassing.

Crusading editor Ebenezer Binns risks his life against extortionists and killers. John Cannon persuades Binns to establish Tucson's first newspaper in hope of running the lawless element out of town. A plot by Hank Pogue, the town boss, to kill the fearless editor fails twice. When Binns starts to print his first edition exposing Pogue's operation, Manolito and Pedro barricade themselves in the newspaper office to protect Binns from Pogue's determined gunmen.

When Victoria saves the life of a man injured in a stagecoach plundered by Comancheros, she learns the man has sworn to kill her husband. The injured man, James Forrest, blames John Cannon for the death of his family in the Civil War. The Comancheros, led by Macklin, capture the wandering pair, who are lost in the desert. Victoria again saves Forrest by convincing the bandits he is John Cannon and worth a high ransom.

Against John Cannon's advice, Mano helps Sean McLaren, an Irish miner, and his friends in their strike against dangerous working conditions. McLaren and his friend Scanlon are sentenced to the chain gang for fighting with Cass Gregg, mine superintendent. Mano helps the two escape. John Cannon favors negotiations to improve conditions while McLaren insists sabotage will provide more direct results. When Scanlon is fatally beaten by Gregg, McLaren decides to destroy the mine, and Manolito appears helpless to stop him.

Victoria, feeling ignored, leaves her husband John but finds little peace of mind at her father's ranch. Manolito joins Victoria at the Montoya Ranch and vies with his father, Don Sebastian Montoya, for the attention of Countess Maria. Victoria objects to the countess until she learns the countess has been through similar quarrels with her own several husbands. Buck persuades John he has taken his wife too much for granted. John finds it difficult to forget ranch work and turn romantic to win Victoria's return.