Outnumbered but determined, Deputy Marshal of Tombstone Wyatt Earp, his older brother Virgil, who is the current City Marshal, his younger brother Morgan, a Tombstone special police officer, and ally Doc Holliday, who was made an officer and given a badge for the occasion, confront and get the best of the Ike Clanton gang in a violent shootout at the O.K. Corral in the Arizona town of Tombstone.

Clanton, a rustler, conspires to have the Earps charged with murder and tried in a court of law. When they are cleared, Virgil runs for re-election as Tombstone City Marshal but is ambushed and maimed by some of Clanton's hired guns. Morgan elects to run for the office in his brother's place, but he is assassinated on election day after winning.

While seeing Virgil and his family off to California for their safety, Earp kills Frank Stillwell, foiling an attempted ambush orchestrated by Clanton. An appointment as a federal marshal then gives him the authority to pursue the others involved in the attacks on his brothers. Doc Holliday, a gambler who has been on the wrong side of the law himself more than once, assembles a posse to support the pursuit. The men locate Pete Spence, "Curly" Bill Brocius, and Andy Warshaw. In each case, Earp manipulates the circumstances to get his target to draw a weapon rather than simply surrendering, thus enabling Earp to kill them legally rather than make an arrest. Holliday calls Earp out on his tactics, but his strength gives out due to his tuberculosis and Earp transports him to a sanitarium in Colorado.

With Clanton weakened, wealthy interests in Tombstone step forward to end the dispute, buying off the men supporting Clanton, which leads him to hide out in Mexico. To entice Earp to remain in Tombstone, the city's leading citizens tell him they are seeking an appointment for him as Chief U.S. Marshal that could one day make him the Adjutant general for the territory. Earp declines to give his answer to the offer immediately but tells Holliday that he is going back to Tombstone to accept the job. Holliday does not believe him and knows Earp is really going to Mexico to track down Clanton with the cooperation of the Mexican federal authorities. Holliday again joins Earp on the mission, which ends with a final showdown in which Earp shoots Clanton dead in a fast-draw duel between the two.

Earp returns to the Colorado sanitarium to visit the ailing Holliday and says goodbye to his friend, telling him this time he really is returning to Tombstone. As he leaves, though, Earp admits to a visiting Tombstone elder that he's leaving the Southwest altogether, intending never to be involved in law enforcement again. Holliday glances at the countryside as his friend rides away and then resumes his poker game with his sanitarium health aide.

This is the second film by John Sturges about these events, following the fictionalized film from ten years earlier, Gunfight at the O.K. Corral, which had featured Burt Lancaster as Earp and Kirk Douglas as Holliday. However, Ike Clanton is killed at the end of the earlier film (during the gunfight at the O.K. Corral itself). In Hour of the Gun, Clanton not only survives the gunfight but is a major antagonist thereafter. Where Gunfight at the O.K. Corral is more about the main gun battle, this film begins with the gunfight and moves forward from there. Hal B. Wallis had scripted everything in the earlier Gunfight at the O.K. Corral, and Sturges was disappointed with that film.^[2] According to critic Paul Brenner, Hour of the Gun is more of a psychological "melancholy character study".^[3]

The film's music is composed by Jerry Goldsmith.^[4]

Garner wrote in his memoirs that he agreed to make the film without reading the script because he thought so highly of Sturges.^[5] Garner also played the lead as Wyatt Earp in a different film more than two decades later, Blake Edwards's Sunset (1988), a comedy thriller based on the 1920s period during which Earp was a technical adviser for silent films.

Hour of the Gun was filmed in the state of Durango, Mexico; at Estudios Churubusco Azteca (studio) in Mexico City, México D.F., Mexico; San Miguel de Allende, Guanajuato, Mexico; and in Torreón, Coahuíla, Mexico.^[6]

At AllMovie, Bruce Eder calls Garner's portrayal of Earp as "taciturn, emotionally repressed, deeply troubled and torn" but criticizes Edward Anhalt's script as being too strict to historical facts and confining the actors, especially Garner.^[2] Roger Ebert from Chicago Sun-Times says: "Garner turns in one of his best performances."^[7]

Hour of the Gun was released to DVD by MGM Home Video May 17, 2005, and later on Blu-ray by Twilight Time. The film was also made available in the digital format.^[8]

• List of American films of 1967

• Hour of the Gun at IMDb  
• Hour of the Gun at Rotten Tomatoes
• Hour of the Gun at the TCM Movie Database
• Hour of the Gun at AllMovie