On Aug. 1, 2008, 11 climbers perished on K2, the deadliest day in the mountain’s history.

At 28,251 feet, K2 is the second-highest mountain in the world. It’s roughly 800 feet shorter than the world’s tallest peak, Mount Everest, but has the reputation of being far more dangerous.

The tragic event on K2 became a major news story in the summer of 2008, although the details of what happened on that day — and why so many people lost their lives — are still murky.

Director Nick Ryan attempts to piece together the story in a documentary called the “The Summit,” which premiered at Sundance earlier this year.

The movie relies on interviews from survivors and uses footage from the actual climb as well as reenactments filmed in the Alps.

Here’s a shortened version of the story, told using screenshots from the trailer, but we recommend seeing the full documentary. It goes on general release in select cities in the United States on Oct. 4.

Located on the western edge of the Himalayas, K2 is found at the center of the Karakoram Mountain range in northern Pakistan.

K2 is slightly shorter than Everest, but more dangerous to mountaineers because it is more difficult to climb and has notoriously bad weather since it is farther north.

Of the roughly 300 climbers who have reached the top of K2, more than one-quarter of them died on the way down.

See the rest of the story at Business Insider