Based on the 1972 novel The Eiger Sanction by Trevanian, the film is about Jonathan Hemlock, an art history professor, mountain climber, and former assassin once employed by a secret government agency, who is blackmailed into returning to his deadly profession for one last mission.

Hemlock agrees to join an international climbing team in Switzerland which is planning an ascent of the Eiger north face to avenge the murder of an old friend.

The picture was filmed on location on the Eiger mountain and Zürich in Switzerland, in Monument Valley and Zion National Park in the American Southwest, and in Carmel-by-the-Sea and Monterey in California.

Art professor and mountaineer, Jonathan Hemlock, 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.

Hemlock agrees, and travels to Zürich, where he carries out the first sanction for $20,000, twice his usual fee (equivalent to $124,000 in 2023), and a letter guaranteeing him that he would receive no trouble from the IRS.

Dragon agrees to pay him $100,000 (equivalent to $618,000 in 2023) plus expenses, and tells him the target is a member of an international mountain-climbing team that will soon attempt an ascent of the north face of the Eiger mountain in Switzerland.

Hemlock travels to Arizona to train at a climbing school run by a friend, Ben Bowman, who whips him back into shape with the help of an attractive Native American woman named George.

On the train ride back to Kleine Scheidegg, Bowman admits he became involved with "the other side" years earlier, but claims he had no idea that Henri Baq would be killed.

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,[10][11] and Eiger represented a way to close out his contract.

[16] 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.

[12] Hoover had made an Academy Award-nominated documentary short titled Solo about his lone ascent of El Capitan in Yosemite National Park.

"[18] 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.

[18] 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.

[20] 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.

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.

[24][23][Note 2] 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.

[25] Stanley blamed Eastwood for the accident because of lack of preparation, describing him both as a director and actor as a "very impatient man who doesn't really plan his pictures or do any homework.

Scenes were shot at numerous locations including: 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.

[19] Additional scenes were 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 also very capable when it came to performing physical stunt work.

[19] 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.

[31] A main theme presented initially on piano evokes a sense of sophistication and mystery, then gives a much jazzier or pop rendition reminiscent of Lalo Schifrin's material.

[31] 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.

[31] The pseudo-baroque piece "Training with George" presents a string arrangement "demonstrating Williams's remarkable versatility while retaining that musical signature that makes all of his scores so recognizably his," according to writer James Southall.

"[33] 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.

Film critic David Sterritt, for example, concluded, "Eastwood's unsubtle directing hammers the story home effectively, with commendable attention to details of performance.

"[37] 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.

"[38] 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.

"[39] 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.

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.