Directed by Nick Ryan. Unrated.

If the statistical odds are one in four that you will die doing a certain activity, isn’t it best to stay home and eat a sandwich? Apparently, none of the mountaineers featured in Nick Ryan’s documentary The Summit, about the 2008 tragedy on K2 in which 11 people perished, thought so. Also, FYI, 8,000 metres and above on K2 is known as the “Death Zone” because when you’re there every cell in your body is “screaming, ‘Oxygen, oxygen, oxygen’ ”, and you can literally feel yourself “starting to die”, as one climber puts it. Okay, then.

In August 2008, many climbing teams—including Americans, Norwegians, South Koreans, Serbians, and Italians—awaited a weather window to make their attempt on K2, Earth’s second-highest peak after Everest, but considered more difficult. The result was everybody went up together, things got traffic-clogged, and when the last climber reached the summit it was near dark. Did you know that descending is more dangerous than ascending? Or, as one guy says, “You realize, ‘Fuck, we have to go down.’ Then the surviving starts.”

Night fell, things happened. Several seracs (huge glacier-ice blocks) collapsed. Climbing lines broke. People disappeared. The doc is a mashup of interviews, actual footage, and re-created events—and the reenactments seriously feel like a horror movie, with mountain as size-large monster. It’s not great watching a human slide down a sheer iceface, their helmet lamp swallowed by the mouth of darkness.

Ryan likes the chronological jump-around, knotting up narrative and viewer like the hapless Korean climbers who fell together, entangled in rope. One gets confused. Uh, what supposedly happened when and to whom? Nevertheless, it’s a gripping, sobering mystery the director—with survivors and pained family members of the deceased—subsequently attempts to unknot. There are conflicting accounts. Over 48 hours on the “Savage Mountain” it would get confusing.

Questions remain, likely forever unanswered. But there’s one only a mountaineer can know: do you attempt to rescue stricken fellow climbers? Or do you “save yourself from K2. It’s the only way.” Or maybe don’t go?