Clint Eastwood plays the title role, in his first appearance as San Francisco Police Department (SFPD) Inspector "Dirty" Harry Callahan.

[4][5][6] A psychopathic sniper, later referred to as "Scorpio", shoots a woman while she swims in a San Francisco skyscraper rooftop pool.

He shoots one robber dead, and holds another at gunpoint with his Smith & Wesson Model 29 revolver, giving him an ultimatum: I know what you're thinking: 'Did he fire six shots or only five?'

They meet at the Mount Davidson cross, where Scorpio beats Harry and admits he intends to kill him and let Ann Mary die.

Harry learns of Scorpio's hospital visit and a doctor reveals that the killer lives in a room at Kezar Stadium.

Scorpio crashes the bus into a dirt mound and flees to a nearby quarry, where he takes a hostage before Harry wounds him.

The script, titled Dead Right, by the husband-and-wife team of Harry Julian Fink and Rita M. Fink, was originally about a hard-edged New York City police inspector, Harry Callahan, who is determined to stop Davis, a serial killer, even if he has to skirt the law and accepted standards of policing, blurring the distinction between criminal and cop, addressing the question of how far a free, democratic society can go to protect itself.

The role of Harry Callahan was offered to John Wayne and Frank Sinatra,[9] and later to Robert Mitchum, Steve McQueen, and Burt Lancaster.

[7] In his 1980 interview with Playboy, George C. Scott claimed that he was initially offered the role, but the script's violent nature led him to turn it down.

When producer Jennings Lang initially could not find an actor to take the role of Callahan, he sold the film rights to ABC Television.

[12] Terrence Malick wrote a draft of the film (dated November 1970) in which the shooter (also named Davis) was a vigilante who killed wealthy criminals who had escaped justice.

He believed the role and plot contradicted his belief in collective responsibility for criminal and social justice and the protection of individual rights.

On December 17, 1970, a Warner Bros. studio press release announced that Clint Eastwood would star in, and produce the film through his company, Malpaso.

In a later novelization of the film, Scorpio was referred to as "Charles Davis", a former mental patient from Springfield, Massachusetts, who murdered his grandparents as a teenager.

Robinson's portrayal was so memorable that after the film was released he was reported to have received several death threats and was forced to get an unlisted telephone number.

As a result, Siegel was forced to halt production briefly and sent Robinson for brief training in order to learn how to fire a gun convincingly.

[24] Screenwriter John Milius owns one of the actual Model 29s used in principal photography in Dirty Harry and Magnum Force.

[25] As of March 2012[update], it is on loan to the National Firearms Museum in Fairfax, Virginia, and is in the Hollywood Guns display in the William B. Ruger Gallery.

[26] Glenn Wright, Eastwood's costume designer since Rawhide, was responsible for creating Callahan's distinctive old-fashioned brown and yellow checked jacket to emphasize his strong values in pursuing crime.

[27] One evening Eastwood and Siegel had been watching the San Francisco 49ers in Kezar Stadium in the last game of the season and thought the eerie Greek amphitheater-like setting would be an excellent location for shooting one of the scenes where Callahan encounters Scorpio.

At the 44th Academy Awards, feminists protested outside the Dorothy Chandler Pavilion, holding up banners that displayed messages such as "Dirty Harry is a Rotten Pig".

[46] Roger Greenspun of The New York Times wrote that "What makes Dirty Harry worth watching, no matter how dumb the story, is Siegel's superb sense of the city, not as a place of moods but as a theater for action.

"[47] In The New Yorker, Pauline Kael wrote that Dirty Harry was "a stunningly well-made genre piece", but also "a deeply immoral movie".

"[48] Kevin Thomas of the Los Angeles Times called it "a high-style film with lowbrow appeal, a movie after which you may dislike yourself for liking it as much as you do".

The site's critics consensus reads: "As tough and taciturn as its no-nonsense hero, Dirty Harry delivers a deceptively layered message without sacrificing an ounce of its solid action impact.

"[24] The benefit world premiere of Dirty Harry was held at Loews Theaters' Market Street Cinema in San Francisco on December 22, 1971.

[77] In October 1972, soon after the release of the movie in Australia, two armed men (one of whom coincidentally had the last name "Eastwood") kidnapped a teacher and six school children in Victoria.

[79] In September 1981, a case occurred in Germany, under circumstances quite similar to the Barbara Mackle kidnapping: A ten-year-old girl, Ursula Herrmann, was buried alive in a box fitted with ventilation, lighting and sanitary systems to be held for ransom.

Eastwood's iconic portrayal of the blunt, cynical, unorthodox detective, who is seemingly in perpetual trouble with his incompetent bosses, set the style for a number of his later roles and a genre of "loose-cannon" cop films.

"[82] Dirty Harry helped popularize the Smith & Wesson Model 29 revolver, chambered for the powerful .44 Magnum cartridge, and initiated an increase in sales of the handgun.