THE MAN
Caldwell was born on August 11, 1978, in Loveland, Colorado, the younger of two children. Lean at five foot nine and 150 pounds, he has the "climber V"—highly developed latissimus dorsi muscles—and much of his upper-body strength is concentrated in his shoulders. Watch him on rock and you see a whippety, swaybacked technician, his feet sticking to the stone as surely as if he were kicking steps in snow. (Contrary to popular belief, climbing isn't only about upper-body strength—the best climbers rely mainly on savvy movement, propelled by the feet, legs, and core.)

Caldwell came to the sport through his father, Mike, who lured him at age three up his first multi-pitch route, above Estes Park, Colorado, with the promise that they'd fly a kite when they topped out. A senior guide at the Colorado Mountain School, Mike moved his family to the windy, spartan town and set out to raise an all-star. Tommy earned "credits" for training—push-ups, pull-ups, sit-ups—applying these toward candy bars and, later, rock shoes. He was only 12 when he first climbed the Diamond, a sinister 1,000-foot wall on nearby Longs Peak.

Throughout the nineties and into the new century, Caldwell left his mark all over Colorado. But he's best known for his unique rapport with El Capitan, a granite wall so intimidating that it sends many accomplished climbers scurrying back to earth. El Cap—100 million years old, two miles wide, scoured to near perfection by glaciers—is home to 90-odd aid climbs and 17 free climbs. Over the years, roughly two dozen people have died there in rappelling mishaps, jumar accidents, and falls, or as a result of massive Sierra storms that can turn the cracks into cataracts or freeze ropes into unusable cable.

Caldwell first caught the El Cap bug in 1997, at 19, during a spectacular failure of a trip with his father, when he attempted to free the Salathé Wall, a 30-plus-pitch climb on the southwest face. The Salathé is hardest on the headwall, a golden shield of rock slashed by a 200-foot crack that consistently overhangs five degrees past vertical, 2,500 feet off the ground.

"I didn't have the stamina, and we didn't have the logistics," Caldwell says. "I'd be climbing with a 30-pound rack, a triple set of cams on one side and four sets of nuts and Tricams on the other." The pair topped out after seven days, with the younger Caldwell having been, he said, "completely bouted" on the hardest free pitches, despite his 5.14 sport-climbing background.

Caldwell had tried the Salathé "on sight," starting from the ground and attempting each pitch with no prior knowledge of how to do it. What he didn't know is that big-wall free climbers often spend time studying a route in advance, rehearsing it and setting up gear stashes. It's not uncommon to aid-climb or rappel the hardest pitches first, placing top ropes to make move-by-move rehearsal easier as the preparations continue. Climbers write down each gear placement and pocket these lists to consult on the fly; store food, water, and sleeping bags to obviate the muscle-crushing drudgery of hauling it all up from the ground; and tote or stash multiple pairs of rock shoes, some sized amply for easier pitches and others toe-crunchingly tight for the hardest leads.

Armed with this newfound knowledge, Caldwell returned in early 1998, humped 80 pounds of gear up the East Ledges, and rapped into the Salathé Headwall to rehearse the crux crack. He returned that April with Mike Cassidy, a climber he'd met in Yosemite Valley, and free-climbed the Salathé in a three-day push.

Since then, Caldwell has spent upwards of 500 days on El Cap, freeing 12 of its routes—five of those being first free ascents. In 2007, to be closer to what he calls his "obsession," he and Rodden took eight months off from climbing to build an airy, three-story, peaked-roof home in Yosemite West, only 12 miles from their theater of operations.