A documentary by Jimmy Chin and Elizabeth Chai Vasarhelyi. Rated PG.

What drives a man to hang in a flimsy tent off a sheer cliff face, 20,000-odd feet above sea level with avalanches audibly rushing down around him? Or to share a high-altitude smoke with his two climbing bros before making his last push up a killer peak?

These are questions that never fully get answered in Meru, but one thing is clear: these guys are fully obsessed. Mixing sweeping views with the back story of three men—Jimmy Chin, Conrad Anker, and Renan Ozturk—who attempt the titular summit in the Himalayas, the documentary captures the real tension and superhuman feats that movies like Everest have to portray through actors. Interestingly, the world’s highest mountain seems like nothing to this trio: codirector Chin has even skied from the top of Everest.

But Meru, and its peak known as the Shark’s Fin, is another story. As expert, F-bomb-dropping commentator Jon Krakauer explains, it has no Sherpas and no fixed ropes to help along its climbers; they must haul hundreds of pounds of tools and food.

The first attempt, early in the movie, goes sideways—and then things get really interesting. The men all retreat to their daily jobs and families, but fate and an epic amount of bad luck bring them back, single-mindedly, to try to conquer the Shark’s Fin once more.

It’s the kind of story that you couldn’t make up, and the film is by turns surprising and heart-pounding. Still, like the recent Sunshine Superman or Everest, Meru never digs too deeply into the complex forces that drive some people to death-defying acts. Perhaps due to the fact that one of the filmmakers is a climber, and the other is his wife, there’s little real analysis of what is, on the surface, an act of insanity. Then again, introspection might not be such a great trait when you’re hanging from a rock face and it’s 20 below.