PROLOGUE February 2012 The tent was possessed. Death Valley''s wind breathed a wicked life into it, whipping it into a writhing demon intent on freeing itself from my grasp and flying off on some maniacal mission. Determined to put it up, I engulfed as much of the tent in my arms as I could, stomped on it with both feet, tugged on the strip of webbing holding a grommet, and strained to bend the tip of the tent pole toward the hole. I howled with effort and the sound tore away on the wind, just as the tent so wanted to. I knew I was breaking my own cardinal rule: Stop When You''re Tired. That rule had burned itself into my brain over the dozen years since I''d first developed the symptoms of chronic fatigue syndrome, the illness I had come to the desert attempting to outwit. Even mild exertion could leave me nearly paralyzed the next day, sometimes unable to turn over in bed. Now I was spending all my strength wrestling with this nylon and fiberglass fiend.

Before I left home, I''d made sure I was capable of setting up this borrowed hurricane-grade tent, but I hadn''t counted on a hurricane-grade wind. I was miles up a jeep trail off a long dirt road in the middle of the godforsaken desert, alone except for my dog. Should I wake up crippled and call for help, my shouts would shred in the wind long before they reached a human ear. On top of all that, I didn''t even much believe in the mission that brought me to the desert in the first place. I had come to Death Valley on the theory that I needed to get clear of mold--from moldy buildings, from mold in the outside air, from mold in my belongings. Strangers on the Internet had told me there was a good chance that mold had triggered my illness and that by strictly avoiding it, I would eventually recover. I had never had any obvious reaction to mold in the past, but my Internet advisors told me that when I returned home after two weeks in the desert, the mold in my own house and belongings would likely make me dramatically sick. And then, at last, I would know what was doing me in.

This whole thing is probably a crock of shit, I''d thought, but at least it''ll make a good story. The truth was, though, that I was desperate to get better. Over the previous year, my health had deteriorated so much that I could barely work, often couldn''t walk, couldn''t even take care of myself. I had gone to the top specialists in the world, and I''d pretty much run out of medical options. I would soon run out of money, too, and I had little family to turn to. I was 39, and I had no idea what was going to happen to me. Consignment to a nursing home? Without that level of desperation, I couldn''t have brought myself to pursue a theory that so many scientists sneered at. I was a science writer and a mathematician, and science was my primary lens for viewing the world.

Coming to Death Valley had unmoored me from both my physical and intellectual homes. The wind tried again to rip the tent away as the last pole snicked into its grommet. Thank god, I thought, clutching the tent harder. I allowed myself only a moment to catch my breath, not wanting to let my exhaustion undo me. Then I began pounding stakes into the ground. My two-year-old puppy, Frances, bounded up to me, her brown nose covered in fine tan sand, and then she ran off in pursuit of a fly. I smiled--she, clearly, wasn''t a bit worried about the tent or the wind. I watched her leap and snap at the invisible insect.

At least I''m not completely alone, I thought. I plodded 50 feet to the car to gather essentials before I ran out of energy. As I reached toward the trunk, I stopped, arrested by the valley that surrounded me. Bands of red and blue and yellow and pink rippled through the mountains facing me, the peaks'' geological story written on their naked flanks for all to read. The Panamint Mountains at my back were ever so slowly listing eastward like a great ship keeling over, the summits twisting higher as the valley floor sank. Salt flats shone white on the valley floor, the residue of millennia of rain that had run off the mountains and evaporated, carrying a load of salt and minerals to join the dried-up remains of Pleistocene lakes. Except for a few tiny cars inching along the road ten miles away, I saw no sign of a human being. I felt myself expand into this great space, this emptiness.

Despite the wind''s immense swirl of energy, the land felt quiet, still, impassive. Everything fell away from me--my body, my pain and exhaustion, my fear, my strange experiment--and was replaced with a huge and ancient stillness. All the time, I thought, this place was here, whether I was pinned to my bed or bounding up a mountain trail. As I poured out into the valley, I felt the valley pouring into me, its enormous spaciousness filling my chest. The wind buffeted me, and I staggered. I returned to my task, gathering a couple days'' worth of food to take to the tent in case I couldn''t make it back to the car the next day. Then I returned for my sleeping bag, pad, and Frances''s blanket. All were new to me--one of the requirements of this experiment was that I leave all my own belongings behind, since everything I owned, on this theory, was contaminated with mold.

The sleeping bag and pad I had borrowed from a friend, and the cheap blanket came from Target. I could only hope they were mold-free. After the weeks of slow preparation, I had made it. It was only 6 p.m., but I was done for. I called Frances into the tent and curled up in my sleeping bag. Before I left for Death Valley, I''d told friends that I felt like I was going to the desert to die.

I fully expected to be breathing at the end of the trip, but I couldn''t keep everything together as I had been doing for years, holding on to my responsibilities and dreams in spite of the barriers my illness threw in my path. Whether the experiment worked or didn''t, the life I had lived was over. I was staring into a cavernous darkness, beyond any imagined future I could invent. I wrapped my arms around my dog and closed my eyes. Okay, I thought. Whatever is next, okay. PART 1 DESCENT CHAPTER 1 CONSTRUCTION AND DESTRUCTION Summer 2000 12 years earlier The cool mud squished between my fingers. It was so thick with chopped straw that I could pick it up by the handful to plaster the straw-bale wall of the house I was building.

I mushed the mud into the bales with both hands, working it deep into the straw in a hypnotic, sensual cadence: Grab, mush. Grab, mush. Grab, mush. The rhythm helped me ignore the exhaustion gnawing at me. A couple dozen friends had spent the day at our plaster party, helping us with the enormous job of mudding all the walls of the house my husband and I were building on our streamside land outside Santa Fe, New Mexico. All day, I hustled to keep everyone busy, teaching people to screen dirt and chop straw and mix mud, answering questions, running around with 35-pound buckets of mud in each hand to keep everyone supplied. After all our friends had left, I gathered up the scraps of plaster left in various buckets and, despite my tiredness, gave myself this great pleasure of plastering a wall with my own hands. I reveled in the softness of the mud and the solidity of the bales--and the simplicity of a task with few decisions to make and no one else to satisfy.

I finished the wall faster than a crew of four of our friends would have. A couple years earlier, the Tewa Indian women who had taught me how to plaster had similarly outpaced me. I stepped back from the wall, and a rush of awe filled me. That mud was now part of a wall that was destined, I hoped, to stand for decades, sheltering me from wind and cold. I imagined that someday my children would play in that spot, bumping against the wall, kept safe by its solidity. It seemed almost impossible that this seemingly endless series of mundane tasks would someday result in a house . Once my job was done, my exhaustion wormed its way into my awareness--carrying my fear along with it. A couple of hours earlier, I had sent my husband, Geoff, inside for the evening, tired of telling him what to do.

Please spray out the mixer. Please gather and wash the buckets. Please put away the screen. It was less painful to do it myself than to deal with his daze. Bits of Geoff''s soul seemed to be disappearing, nibbled away by bipolar disorder. As hard as I was working to construct our house, I couldn''t keep up with the destruction overtaking him--and us. At one point recently, Geoff had come to me with eyes alight. "Look!" he said, handing me an eight-inch scrap of rebar, the material we had used to reinforce the concrete in our foundation.

Rebar was ordinarily a dull, rusty brown rod, studded with bumps to help the concrete adhere to the steel--but the end of this piece was so smooth it felt soft against my finger, and blue and gray seemed to swirl inside the metal. Geoff held a file in his other hand, and metal dust lay at his feet. "It''s so shiny!" he said, in a five-year-old''s voice. The wonder in his eyes nearly brought tears to mine. I hadn''t seen a moment of joy in him for months. If a shiny bit of metal could bring that back to him, could remind him that life had pleasures that made the fight against the depression worth it, that he wasn''t better off dead--well, it made me want to enshrine the thing.