Life-or-death choices - on the side of a mountain

Why do people climb mountains? Especially towering ones where it's bitterly cold, the air is so thin it's hardly there, and thousand-foot falls are just a misstep away? Places that make acrophobes like me want to hide under our seats even when they're safely confined to a movie screen?

You won't get answers to these questions in "Touching the Void," which takes mountaineering for granted as an exhilarating sport. What you will get is a vivid, gripping account of a real-life climb that ran into every life-threatening disaster you can think of, yet resulted in success for the pair who took it on. In fact, they survived in good enough spirits to hit the slopes again once they'd recovered.

The climbers, Joe Simpson and Simon Yates, set out in 1985 to scale the Siula Grande in the Peruvian Alps, hoping to make the first full ascent of its western face. Sturdy young Englishmen that they were, they had only one companion watching their base camp, and made no arrangements for rescue.

Reaching the pinnacle was difficult, but they managed it in three days and enjoyed the view from the summit.

Then, during the descent, Mr. Simpson took a tumble and broke his leg. The two kept heading down, though, alternately lowering each other with the rope that tied them together.

Then, further disaster. At one point the slope took an inward curve, though, leaving Simpson dangling over a deep crevasse with no way of touching the mountainside. Unable to see or hear what was happening below, Yates held the rope as long as possible, then realized they would both soon plummet to their deaths. Faced with the agonizing decision, he opted to cut the rope and continue his descent, convinced his partner was lying lifeless in the snows beneath.

But he wasn't. Simpson had fallen into the crevasse, and eventually he lowered himself still farther and found a way out. Then he made an unbelievably arduous trek toward the base camp without even knowing his companions would still be there to keep what was left of him alive.

No cameras were present to capture all this, so filmmaker Kevin Macdonald has restaged the events almost 20 years later. This makes "Touching the Void" not a true documentary but a docudrama - a form that's easily abused, as the tacky recreations on TV history shows often prove.

Mr. Macdonald avoids the format's pitfalls, however, alternating views of the restaged climb - using stunt doubles in similar locations - with interviews in which the real Simpson and Yates recall the disasters they endured.

They also briefly discuss the controversy they encountered back in England, where many in the climbing community criticized Yates for breaking a taboo by cutting the rope.

Don't miss this harrowing movie if you're in the mood for adventure more thrilling than anything Hollywood has to offer these days.

• Not rated; contains scenes of pain.