Principal photography started on August 12, 1974, and ended in late September 1974. The picture was filmed on location on the Eiger mountain and Zurich in Switzerland, in Monument Valley and Zion National Park in the American Southwest, and in Carmel-by-the-Sea and Monterey in California. Special equipment and handheld cameras were employed to film the climbing sequences. Eastwood did his own climbing and stuntwork under dangerous conditions. Twenty-six-year-old British climber David Knowles died on the Eiger during the production. The film score was composed by John Williams.
Art professor and mountaineer Jonathan Hemlock (Clint Eastwood) is a retired government assassin called on to return to work for two more "sanctions", a euphemism for officially approved killings. During his career with a secret government agency called "C2", Hemlock amassed a private collection of 21 rare masterpiece paintings, paid for from his previous sanctions. The director of C2, Dragon (Thayer David), is an albino ex-Nazi confined to semi-darkness and kept alive by blood transfusions. Dragon wants Hemlock to kill two men responsible for the death of another government agent, code name Wormwood. Insisting he is retired, Hemlock refuses until Dragon threatens to expose Hemlock's art collection to the IRS. Hemlock agrees, and travels to Zurich, where he carries out the first sanction for $20,000, twice his usual fee, and a letter guaranteeing no trouble from the IRS.
Returning from Europe, Hemlock meets C2 courier Jemima Brown (Vonetta McGee), who seduces him and steals his money and IRS exemption letter. Dragon agrees to return them if Hemlock completes the second sanction. Hemlock is reluctant, but agrees when he learns that the C2 agent killed, Wormwood, was in fact his old friend Henri Baq. Dragon agrees to pay him $100,000 plus expenses, and tells him the target is a member of an international mountain climbing team that will attempt an ascent of the north face of the Eiger mountain in Switzerland. Hemlock will be the American member of the team, and must kill one of the climbers—Dragon is unsure of the target's identity, but confirms that the man walks with a limp.
Hemlock travels to Arizona to train at a climbing school run by a friend, Ben Bowman (George Kennedy), who whips him back into shape with the help of an attractive Native American woman named George (later revealed to be Bowman's daughter). Hemlock also encounters an enemy, Miles Mellough (Jack Cassidy), a former ally from the military who betrayed him in Southeast Asia. Mellough tries to kill Hemlock by hiring George to drug him, but Hemlock survives. Later he lures Mellough and his bodyguard into the desert, where he shoots the bodyguard and leaves Mellough to die in the sun.
Hemlock travels to Switzerland with Bowman, the "ground man" or supervisor of the climb, and meets the other members of the climbing party at the Hotel Bellevue des Alpes at Kleine Scheidegg. The headstrong and condescending German member, Karl Freytag (Reiner Schöne), presents his proposed route up the mountain, and the team agrees that he will lead the party. The following morning, the men begin their ascent of the Eiger north face, and soon the weather conditions become poor. The French climber is struck by falling rocks and later dies. With Hemlock now leading, the surviving members retreat towards a tunnel window that connects to a railroad station inside the mountain, carrying the dead climber between them. At the last moment, Freytag and the Austrian, Anderl Meyer (Michael Grimm), fall to their deaths. Hemlock is saved, dangling alone a few meters from the tunnel window.
Bowman and a rescue crew make their way through the Eiger to the tunnel window, where they attempt to throw a rope to Hemlock. Hemlock notices Bowman is limping, a sign that identifies him as Hemlock's target. Hemlock says, "You're limping, Ben," reluctant to trust that Bowman will rescue him. Bowman throws him the rope, and Hemlock attaches it, then reluctantly cuts his own rope. He falls onto Bowman's rope, and is pulled into the tunnel to safety. On the train back to Kleine Scheidegg, Bowman admits he became involved with "the other side" years earlier and had no idea there would be a killing. Bowman admits he had become involved with Miles Mellough to whom he was indebted for getting his daughter George off drugs.
Back at Kleine Scheidegg, Bowman approaches Hemlock, looking to mend his relationship with the assassin. Hemlock tells him that C2 believes the target died on the mountain, and that there is no reason to tell them otherwise. After Bowman leaves, Jemima Brown joins Hemlock, who takes a phone call from Dragon, who is convinced that Hemlock killed all three of the other climbers intentionally to ensure he killed the target. Jemima wonders if Dragon is correct.
The film is based on the 1972 thriller novel The Eiger Sanction by Trevanian, a pseudonym for Rodney William Whitaker, a University of Texas film professor. It was Trevanian's first novel and was written as an intentional spoof of James Bond novels. Universal Studios purchased the film rights in November 1972, soon after the novel was published. In late November 1972 screenwriter Hal Dresner was hired to adapt the novel with the author Trevanian, credited as Rod Whitaker as a screenwriter. In April 1973 Paul Newman was cast in the lead role of Jonathan Hemlock. Dresner and Trevanian prepared two drafts of the screenplay, which were provided to Newman. Disappointed with the results and believing the story was too violent, Newman opted out of the project. In late 1973 Universal producers Richard D. Zanuck and David Brown approached Eastwood with the project. Eastwood saw serious flaws with the novel and the script, which had gone through three revisions and a rewrite by the time he read it. Eastwood was never interested in espionage as a subject or the spy thriller as a genre, but he was attracted to the project for two reasons. Disappointed with the way Universal handled his first directorial efforts—Play Misty for Me (1971) and Breezy (1973)—he was looking to move to Warner Bros. where studio head Frank Wells was offering an open invitation, and Eiger represented a way to close out his contract. More importantly, the project offered him the opportunity to work in relative isolation on location in Switzerland away from the distractions of the studio and to work efficiently with a small cast and crew. On January 31, 1974, Universal announced that Eastwood was contracted to both star in and co-produce The Eiger Sanction with his own Malpaso Productions and Universal Pictures.
In a 1976 interview with author Patrick McGilligan for Focus on Film, Eastwood described the essential problems with the novel: "The book has no ties. In other words, the character that is killed at the beginning has no relationship to anybody else. I just took it and tried to make the guy relate to the hero so the hero had some motivations. The way the book was written, he had no motivations for anything. He just went up there strictly for monetary gain, no other motivation, period." Believing that improvements could be made to the script, Eastwood contacted novelist Warren B. Murphy — known for his The Destroyer assassin series — in February 1974 and asked for his assistance, despite Murphy's having never read the book nor written for a film before. Murphy read the novel and agreed to write the script, but he was unhappy with the novel's tone, which he believed patronized readers. Murphy completed a draft in late March and a revised script a month later. Eastwood also felt that the authenticity of the climbing sequences he envisioned would compensate for the narrative's shortcomings. From the beginning, Eastwood planned to shoot the mountaineering scenes on location, and that he would do his own climbing without a stunt double. "The challenge of it for me," he would later explain, "was to actually shoot a mountain-type film on a mountain, not on sets. The only ones done in the past were all done on sets; the mountains were all papier-mâché mountains." In late May 1974, Universal announced that Eastwood would also direct the film, and that principal photography was scheduled to start on August 1, 1974, at the Eiger mountain in Switzerland. Universal's vice-president Jennings Lang would supervise the production.
As soon as he signed on to the project, Eastwood took complete control of the production. He worked with soundman Peter Pilafian to develop lightweight, disposable batteries to power a specially adapted camera and sound equipment needed to film on the mountain. He also hired Mike Hoover to serve as climbing adviser for the film. Hoover had made an Academy Award nominated documentary short titled Solo about his lone ascent of El Capitan in Yosemite National Park. Eastwood had seen and admired the documentary, and hired Hoover to train him on how to look professional during the climbing scenes, and to serve as principal cameraman on the more dangerous climbing sequences. Intent on doing his own climbing for the film, Eastwood accompanied Hoover to Yosemite in early July to train and climb the 1,200-foot (370 m) Lost Arrow Spire, a detached pillar in Yosemite Valley located adjacent to Upper Yosemite Falls. While he had done some rock climbing in his youth, the forty-four year old Eastwood was not prepared for the levels of difficulty presented by the climb. Hoover would later recall, "He looked up at me and said, 'Gee, I don't think I can make it.' I said, 'Well, Clint, you really don't have much choice, do you?' Then he reacted characteristically—he got pissed off. He pulled in his chin and gritted his teeth and with absolutely no technique at all, just blood and guts, he mossed his way up. No skill, no brains, just pure muscle."
Meanwhile, George Kennedy, who had recently finished filming Thunderbolt and Lightfoot with Eastwood, was cast as Ben Bowman, Hemlock's friend and former climbing partner. Jack Cassidy was cast as the colorful and flamboyantly gay assassin Miles Mellough. Thayer David, a year before his role as a boxing promoter in Rocky, was cast as the albino Dragon (named "Yurasis Dragon" in the novel). Just prior to the start of filming, Vonetta McGee was cast as the African-American female C2 operative, Jemima Brown. In late July 1974, Eastwood, Kennedy, Hoover, and a small crew traveled to Monument Valley—director John Ford's favorite location for his Westerns—on the Arizona-Utah border to film a sequence that would be used in the film as a practice climb by the main characters of the Totem Pole, a 640-foot (200 m) rock spire with an 18-foot (5.5 m) diameter. Located within the lands of the Navajo Nation, the Totem Pole had religious significance to the Navajos who prohibited climbs on the formation. Hoover negotiated permission from the tribal authorities for his team to climb the Totem Pole to remove pitons and other climbing hardware embedded in the structure by previous climbers, restoring the monolith to pristine condition. The ascent was made by two climbers from Moab, Eric Bjornstad and Ken Wyrick, who were tasked with preparing the summit for the helicopter film crew and removing existing hardware. Upon attaining the summit, they were helicoptered off and Eastwood and Kennedy were lowered onto the eighteen-foot wide summit for one of Eastwood's happiest film-making memories, watching the sun setting over Monument Valley where many classic Westerns were filmed.
Principal photography began on August 12, 1974 in Grindelwald, Switzerland, with a team of climbing experts and advisers from the United States, Canada, Germany, Switzerland, and the United Kingdom. The climbers were based at the Hotel Bellevue des Alpes at Kleine Scheidegg, located below and between the Eiger and Lauberhorn peaks in the Bernese Oberland region. At 13,015 feet (3,967 m) in elevation, the north face of the Eiger, which means ogre in German, is renowned for its treacherous climbing, earning the German nickname Mordwand or "murder wall". By 1974, forty-one climbers had lost their lives trying to climb the forbidding edifice. Eastwood decided to take on the most dangerous work during the first two days of shooting. By midafternoon on August 13, as light began to fail, a wrap was called after shooting a rock slide sequence. While the team was preparing to be helicoptered off the north face, Hoover remembered they had not taken any footage from the climbers' point of view of the boulders crashing down on them. With his handheld camera, Hoover and twenty-six-year-old British climber David Knowles rappelled down to the ledge and took the needed footage. As they were gathering their gear, a huge rock broke free and smashed into the climbers, killing Knowles and leaving Hoover with a fractured pelvis and severely bruised muscles. Following an impromptu wake for Knowles, Eastwood considered canceling the production, but the climbers persuaded him to continue on, assuring him that they all knew the risks of their trade and did not want Knowles' death to be meaningless.
Eastwood insisted on doing all his own climbing and stunts—a decision met with disapproval by the director of the International School of Mountaineering, Dougal Haston, who experienced the dangers of the Eiger first hand having been with American climber John Harlin when he fell to his death. Cameraman Frank Stanley also thought climbing the perilous mountain to shoot a film was unnecessary. While filming on the Eiger, Stanley fell and sustained injuries that forced him to use a wheelchair for some time. Stanley blamed Eastwood for the accident because of lack of preparation, describing him as a director and actor as a "very impatient man who doesn't really plan his pictures or do any homework". One of the most dangerous stunts that Eastwood ever attempted involved him hanging from a rope four thousand feet above the valley floor in the penultimate scene. The scene required him to cut himself free so he could be pulled to safety by his rescuers. As he cuts the rope supporting his weight, he drops precariously before being saved by a rigged cable. Eastwood would later say, "I didn't want to use a stunt man, because I wanted to use a telephoto lens and zoom in slowly all the way to my face—so you could see it was really me." After five weeks at the Eiger, the production unit traveled to Zurich to film the opening scenes of the film around the area of the Grossmünster cathedral and the Limmat river, the Münsterbrücke bridge, the Café Bauschänzli, the Kirchgasse, the Napfgasse, and the Restaurant Karl der Grosse.
Eastwood and company returned to the United States to the American Southwest where filming resumed in Zion National Park in Utah, where scenes were shot at Zion-Mount Carmel Highway, Zion Lodge, Checkerboard Mesa, the Narrows, the Hanging Gardens, the bridge over the Virgin River, and the Cave Route below the Cerberus Gendarme. Additional scenes were also shot in Monument Valley at the Tyrolean Transfer, where a rope had been rigged by climber Eric Bjornstad, who noted that Eastwood was not only very fit but very capable when it came to performing physical stuntwork like this. Scenes were also shot at Rock Door mesa above Goulding's Lodge, where Eastwood and company stayed. After completing principal photography in late September 1974 in Carmel-by-the-Sea and Monterey in California, Eastwood hosted the cast and crew at his restaurant, the Hog's Breath Inn, for a wrap party. The Eiger Sanction was filmed in Technicolor, and was released to theaters with an aspect ratio of 2.35 : 1.
Eastwood chose John Williams to compose the original music soundtrack for The Eiger Sanction—his only score in the spy thriller genre. A main theme is presented initially on piano evoking a sense of sophistication and mystery, then given a much jazzier or pop rendition reminiscent of Lalo Schifrin's material. The most impressive sections of the score are the grand orchestral cues composed for the mountain scenes—pieces such as "The Icy Ascent" and "The Top of the World" capture both the beauty of the alpine surroundings and the inherent dangers. The latter title presents the kind of rapturous orchestral celebration now commonly associated with Williams' music. The pseudo-baroque piece "Training with George" presents a lovely string arrangement "demonstrating Williams's remarkable versatility while retaining that musical signature that makes all of his scores so recognisably his", according to writer James Southall. The main theme is reprised in "George Sets the Pace" as a guitar solo with flute harmony. "Microfilm" is a low key action piece, and "Up the Drainpipe" is pure suspense music—different in tone from the rest of the album. The album concludes with "The Eiger", a triumphant and beautiful finale. Although not considered among Williams' finest scores, The Eiger Sanction soundtrack has a certain stylish allure different from anything else he's done, and is "memorable in some places, beautiful and orchestral in others", according to Southall. The original soundtrack album was released in 1975 on the MCA label, and in 1991 it was issued as a CD on the Varèse Sarabande label.
The Eiger Sanction premiered in New York City on May 21, 1975.
The Eiger Sanction received mixed reviews upon its theatrical release. The general reaction among many reviewers offered criticism for the story and screenplay, and praise for the climbing footage and action sequences. Variety concluded, "Eastwood ... manages fine suspense both in the Swiss and Monument Valley climbs, as well as delineation of character. His direction displays a knowledge that permits rugged action." The New York Times reviewer described the film as "a long, foolish but never boring suspense melodrama" that compensates for its plot shortcomings with "stunning" climbing sequences that look "difficult and very beautiful". In his review in the Chicago Sun-Times, Roger Ebert gave the film three out of four stars, writing, "It has a plot so unlikely and confused that we can't believe it for much more than 15 seconds at a time, but its action sequences are so absorbing and its mountaintop photography so compelling that we don't care ... and so we get wrapped up in the situations, and we're seduced by the photography, and we enjoy the several pretty girls who happen along in the hero's path, and if the plot doesn't make any sense well, no movie's perfect." Playboy magazine described the film as "a James Bond reject." Some critics were less forgiving, such as Joy Gould Boyum of The Wall Street Journal who complained that the film "situates villainy in homosexuals and physically disabled men", and Pauline Kael of New York magazine who described the film as "a total travesty".
More recent critics have treated the film and Eastwood's direction in a more positive light. Film critic David Sterritt, for example, concluded that "Eastwood's unsubtle directing hammers the story home effectively, with commendable attention to details of performance". In his review on the Combustible Celluloid website, Jeffrey M. Anderson gave the film three and a half out of four stars, calling it "surprisingly effective, even by today's standards". Anderson found the climbing footage "truly gripping" and that the film was "underrated, high-water mark for the great director". Christopher Granger in the Tampa Bay Movie Examiner gave the film four out of five stars, writing, "The scenery in the Alps is breathtaking and the action in this spy thriller is end of your seat viewing." Jason Ivey in the Tea Party Tribune found the later sequences of the film "truly breathtaking" and wrote, "There's simply something more suspenseful, more dramatic, when you know you're watching Clint Eastwood hanging from a rope 1,000 feet above the rocky earth." Ivey concluded:
The images created on screen by Eastwood, his stunt, mountaineering, and camera teams, and the landscapes themselves are incredible. They elevate an otherwise silly plot, marking a moment in movie history when the images committed to film were far more real than today's mix of live action and cartoons. This realness makes films like this compelling in a way today's films can never be.
The film, which operated on a budget of $9 million, earned $14,200,000 at the box office.
The Eiger Sanction was first released in DVD format on December 15, 1998 by Universal Studios, with subsequent re-releases on April 14, 2003, February 10, 2009, and May 5, 2015. The film was released in Blu-ray format on November 10, 2015 by Universal.