On May 6, around 10:30 p.m., the two left the Potter home in Moab to check out Delicate Arch. They drove into the park and hiked the 1.5-mile trail from the parking lot up an incline to the formation. With few or no places to slot protective gear like nuts or cams—and with the distinct possibility of ripping off a hold—the men decided they needed to put a rope over the top first. Exactly how they did that is still a mystery—a secret that neither Potter nor Lynch will reveal, with Lynch coyly calling it "an old magician's trick."

But there are theories. One easy way is a method that's been used by desert climbers for decades: shooting an arrow over the arch with a string attached, then using that string to haul up a heavier climbing rope. It's a common technique, but it's illegal in a national park, and Lynch strongly denies that this was the trick. "We did not use a freaking bow and arrow," he says. "That's the obvious thing you think of, but no." Another theory: They used a "monkey's fist," basically a wadded knot of rope that one could conceivably launch with an oversize slingshot or whack with a bat over the arch.

Potter won't cop to that, either. "I'm not going to tell people how to do it, because I do think that only the most experienced people should take on climbs of that magnitude," he says.

However the Magic Potter Rope was placed, Lynch weighted one end of it while Potter affixed a Petzl Mini Traxion—a self-ratcheting pulley tethered to his harness—to the other. That tool allowed Potter to climb up the rock freely, with the Mini Traxion slipping along the stationary rope. Should Potter fall, the gizmo would instantly cam, automatically pinching the rope and stopping him from rocketing down the face. That way, Lynch says, the rope wouldn't "saw" across the rock as it might with a traditional top-rope rigging.

Potter climbed the face, choosing to use small depressions in the rock for holds rather than breakable nubs. Following the blue cone of light from a headlamp, he reached the top without a hitch. Once there, Lynch says, Potter set up an anchor with four cams stuck in a horizontal crack in the cap of harder rock on the summit. He says Potter fed the rope off the top along a crack to prevent the rope from rubbing the rock. Lynch then affixed a similar camming device to the rope and climbed up the cord like an inchworm, dangling in space beneath the summit. The top isn't big, maybe 30 feet long by ten feet wide, and it rolls sharply to either side like a donut stuck in the sand. Lynch says he and Potter sat there for "hours, an hour, who knows," watching shooting stars rip across the clear Utah sky.

"We were all alone, just me and him," Potter says. "It was beautiful."

Around 2:30 a.m., Potter called his wife, Steph, who was back at their Moab home with Katie Arnold, a friend and Outside's managing editor. Arnold was visiting for the weekend and had no clue at that point that a Delicate Arch climb was under way.

Davis made coffee and soon she, Arnold, and Perlman—a writer and photographer—drove Perlman's rented Toyota Corolla into the park, just as day began to seep into the eastern sky. When they arrived at the arch, Potter had finished rehearsing—it's unclear exactly how long he practiced—and no ropes were visibly dangling off the arch. Lynch and Potter sat on the rock next to a mound of gear. Steph gave them coffee. As the sun started to warm things up, Potter set off on his first solo ascent, his mane of hair flowing off his six-five frame. Perlman, Lynch, and Davis shot video and stills, while Arnold watched.

Every time Potter got to the top, he pulled a coil of thin rope from a pocket and lowered it off the side to haul up a climbing rope and harness. He rappelled off slowly. At one point, Perlman ascended the rope to capture video of his friend climbing up the steep east route from above. When they were done, everyone packed up and left. The Potters and Arnold went to breakfast. Exhausted, Dean fell asleep over an egg sandwich.