Elisa Rosales lay on her back, head spinning, gasping for air. Her bike lay a few feet away, right where she had dropped it. Darkness pressed at the edges of her vision, and she fought the pull to let go, to drift into sleep. The ground beneath her was cold; she was cold. This was her first motorcycle adventure. She and her husband had set out from Argentina, bound for Arizona, but that destination felt impossibly far from where she now lay in the Andes, at nearly 16,000 feet. And the hardest part of the journey was only beginning.