Alex Honnold, the subject of “Free Solo,” is a man given to extreme focus, obsessive drive, and a highly spartan lifestyle, meaning he lives out of a van and mostly eats cans of beans warmed on a hot plate. His personality matches his ascetic lifestyle; Honnold doesn’t talk much and is prone to bluntness when he does speak. But though he might appear monklike, Honnold is quite the opposite. He’s a thrill seeker of the highest order, a rock climber with a particular fascination for “free soloing,” which involves scaling sheer cliffs alone without ropes, harnesses, or any protective equipment.

Why does Honnold do this? That’s not what the directors Elizabeth Chai Vasarhelyi and Jimmy Chin are interested in. It’s a question that’s probably impossible to answer, since there’s no real rational justification of an activity that promises certain death if you make a single mistake. “Free Solo,” instead, is largely about the intensity of knowing a person like Honnold, of having someone so unusual in your life, and the ways in which he bewitches, excites, and frightens the people around him simply by doing his job.

The mission in “Free Solo” is climbing El Capitan, the 3,000-foot granite cliff in Yosemite Valley that was once thought unclimbable by any method, let alone free soloing. But the secret star of the film is Sanni McCandless, Honnold’s girlfriend, who somehow manages to tunnel through the deep bedrock of Honnold’s disposition and connect with him. Though “Free Solo” is following Honnold as he meticulously plots the path to climbing up El Capitan with only his hands and feet, it’s just as thrilling to watch McCandless try to convince him to live a slightly more normal, settled-down life.

Vasarhelyi and Chin, a married couple, are no strangers to climbing. The last film they made together was 2015’s excellent “Meru,” which was about Chin’s efforts to summit Meru Peak in the Himalayas and the grander metaphorical meanings climbers can assign to such quests. Scaling El Capitan without ropes is something that has literally never been done, and it’s so complex that it requires Honnold to plan out every moment of the route by climbing it with ropes and safety gear, over and over again. That process means that Honnold, the filmmakers, and McCandless are acutely aware of the hazards ahead.

The result is a documentary that’s fascinated with its subject without being reverent, one that’s beautifully photographed without ignoring the horrifying consequences lurking if he fails.

Honnold exists in a community that’s besieged with death; all of the climbers he meets up with and talks to over the course of the film have a fatalistic air to them. But even within this group, Honnold is regarded as a risk taker. In “Alone on the Wall,” a memoir published not long before he began his first preparations for El Capitan, Honnold describes his mentality during a climb as “empty.” He’s aware of the danger — there’s not much room for recklessness in free soloing — but his success partly requires him to not think about his potential death and injury.

As “Free Solo” progresses, the bond between Honnold and McCandless grows stronger, enough to lure him out of his van lifestyle and into a home in Las Vegas. But that only makes his plans for El Capitan that much scarier.

(SD-Agencies)