"Yee-hah!"

His pre-ride rocket fuel-two cans of Red Bull-had given him one heck of a caffeine high. He was buzzed and in the zone, shredding the trail and carving the corners like a downhill skier in the Olympics; the knobby Kevlar tires bit into Mother Earth like a pit bull's teeth into soft human flesh. He veered around blackened trunks of burned-out oak trees then flew through a tunnel of thick brush and pruned a few low-hanging limbs, all just a blur in his peripheral vision. He hit a monster bump and caught air for ten feet; he bounced hard on reentry but maintained his position in the cockpit. One slip and he would tumble down the ravine to a certain death-the thought of which triggered the rush. Adrenaline surged through his being like a narcotic, supercharging his mind and body.

Andy Prescott had never felt more alive.

He was wearing cargo shorts, Converse sneakers, and a T-shirt he had sweated through in the heat and humidity of late August in Texas. His only accessories were a pair of cheap sunglasses, the CamelBak strapped to his back that packed his personal effects and one hundred ounces of Endurox R4-the sports drink of choice for extreme athletes-and the crash helmet. Andy Prescott was crazy but not stupid.

"Slow down, Andy!"

They always came out early on Sunday morning because they didn't have anchors holding them at home-although Tres was living on borrowed time; his girlfriend was already plotting marriage and offspring-and because weekend walkers, hikers, joggers, and your less adventuresome bikers wisely stayed on the family-friendly double-track down by the creek a hundred feet below them. Which meant they could hammer the back trails without fear of pedestrian injury.