The neurologist's name is Dr. Kessler. She has kind eyes and a terrible poker face, which I appreciate. Some doctors try to manage your emotions for you - soften the blow, frame things optimistically, give you hope that isn't warranted by the data. Dr. Kessler just looks sad.

  "The results came back consistent with our preliminary assessment," she says. "I'm sorry, Joshua. It's CJD."

  Creutzfeldt-Jakob disease. I looked it up after the first round of tests, when they started using words like "prion" and "spongiform" and scheduling me for more scans than seemed reasonable for what I thought was just bad insomnia and some coordination issues.

  Prion diseases don't have treatments. They don't have cures. They have trajectories - predictable, measurable, inevitable. The proteins in your brain misfold, and the misfolded proteins cause other proteins to misfold, and the cascade continues until your brain looks like Swiss cheese and you die. Average survival time from diagnosis: four to six months.

  "How certain?" I ask.

  Dr. Kessler blinks. Most patients probably don't ask that. Most patients are crying, or bargaining, or demanding second opinions. But I need to know the error bars before I can process the data.

  "Very certain," she says carefully. "The combination of your symptoms, the MRI findings, and the CSF markers... I wish I could tell you there was meaningful doubt, but there isn't. I'm sorry."

  I nod. That's what I expected. The research I'd done suggested the diagnostic accuracy was somewhere north of 95% when all the indicators aligned. Mine aligned.

  "What happens now?"

  She walks me through it. The progression. What to expect in the first weeks, the first months. Personality changes - irritability, depression, mood swings. Then cognitive decline. Memory problems. Difficulty with speech, with movement, with basic self-care. Eventually, a vegetative state. Then death.

  "We can manage symptoms," she says. "Keep you comfortable. There are support groups, counseling services for you and your family. We'll do everything we can to maintain your quality of life for as long as possible."

  Quality of life. That's a phrase that means something different when you're twenty-two than when you're seventy. At seventy, quality of life means managing pain, staying mobile, keeping your independence. At twenty-two, quality of life means having a life. Plans. Futures. The reasonable expectation that the choices you make today will matter tomorrow.

  I don't have that anymore. I watch it all vanish instantaneously, like a magician snapping their fingers. Vanishing the rabbit.

  "Thank you," I say. "I'd like some time to process this before we discuss next steps."

  Dr. Kessler nods. She gives me pamphlets. Resources. A follow-up appointment card. I take them because it would be rude not to, even though I already know I won't be using most of them.

  The next two weeks are administrative.

  I'm not being dramatic about this. There's genuinely a lot of paperwork involved in dying. I have a small life insurance policy from my first job out of college - not much, but enough to cover funeral costs and leave my parents something. I need to make sure the beneficiary information is current. I need to update my will, such as it is. I need to figure out what to do with my apartment, my car, my books.

  I tell my parents on day three. My mother cries. My father goes very quiet and then excuses himself to the garage, where I suspect he also cries. My sister flies in from Portland and hugs me for a long time without saying anything. Portland to Boston, huh? I spend a small period of my remaining time marveling at the fact that we can just throw people through the air and it works.

  I explain what's going to happen. The timeline. The progression. I use clinical language because it helps me stay detached, and because I think it helps them understand that this is real, that I've accepted it, that I'm not going to spend my remaining months in denial.

  "I want to take a trip," I tell them. "While I'm still... me. See somewhere I've never been. I have some savings. Enough for a few weeks somewhere quiet."

  My mother starts to object - shouldn't I stay close to my doctors, my support system, the people who love me? But my father puts a hand on her arm and she stops.

  You might be reading a pirated copy. Look for the official release to support the author.

  "Where?" he asks.

  "I'm not sure yet. Somewhere with good scenery. Mountains, maybe. Or the coast. Maybe near Yellowstone."

  "You'll stay in touch?"

  This is the hard part. I've thought about how to phrase this, and I still don't have a good answer.

  "I'll try," I say. "But I want you to be prepared for the possibility that I won't come back. Not because something went wrong - just because I might decide that's where I want to... stop."

  My mother's face crumples. My sister grabs my hand. My father just nods, slowly, like he's been waiting for me to say this.

  "You're allowed to do it however you need to," he says. "We'll be okay. Eventually."

  I don't know if that's true. But I appreciate him saying it. It's a long conversation from there. It doesn't get any better for anyone else, either.

  I settle on California.

  Not the California of movies and postcards - the beaches, the palm trees, the Hollywood sign. The other California. The empty parts. The places where the geology is still trying to kill you.

  Mammoth Lakes is a ski resort town in the Eastern Sierra, built in the shadow of a volcanic system that last erupted about seven hundred years ago. The volcano isn't dead - it's sleeping. And while it sleeps, it vents carbon dioxide through the soil. There are places in the forest where the CO2 concentrations are high enough to kill you. Trees die in patches. Animals wander into low-lying areas and don't wander out. Signs warn hikers to avoid certain ravines, certain depressions, anywhere the air might pool and settle.

  It's a strange place to choose. I know that. But there's something appropriate about it. The ground is beautiful and the air is poison and the whole landscape is just waiting for something to change.

  I rent a cabin on the outskirts of town. Nothing fancy - just a bedroom, a kitchenette, a porch with a view of the mountains. I bring books I've been meaning to read. I bring my laptop, though I'm not sure what I'll use it for. Do you need to compose a suicide note in a situation like this? Is it really suicide, or just trying to figure out how to die with meaning? I bring warm clothes, because the altitude is high and the nights are cold, even in summer.

  The first week, I mostly walk. There are trails everywhere - through the forest, along the lakes, up into the higher elevations where the air thins and the views stretch for miles. I move slowly. My coordination isn't what it used to be; the disease is already working on my cerebellum, making me clumsy, uncertain on uneven ground. But I can still walk. I can still see. I can still think clearly, mostly, though I've started forgetting small things - where I put my keys, what I was about to say, the name of the book I finished yesterday.

  The forgetting is the worst part. Not because of what it costs me now, but because of what it promises. Soon it won't be keys and book titles. It will be faces. Names. The people I love. Myself. Then I'll start soiling myself, and the organs will begin to fail one by one like someone disconnecting wires on a bomb panel.

  I'd rather not be there for that part.

  On day ten, I find the spot.

  It's not marked on any map. I've been exploring the areas the signs warn you about - the depressions, the ravines, the places where the CO2 pools. Most of them are fine if you're standing up. The gas is heavier than air; it settles into low spots. As long as you stay on high ground, you're okay.

  But there's a place, maybe a mile off the main trail, where a small cave opens into the hillside. Not deep - maybe twenty feet before it dead-ends. But the entrance is below grade, and the interior is lower still, and when I crouch at the mouth of it I can feel the air change. Thicker. Sweeter. Wrong.

  I don't go in. Not yet. I just sit at the entrance for a while, looking at the trees and the sky and the distant mountains, breathing the good air while I still can.

  I think about my parents. My sister. The life I was supposed to have - the career, the relationships, the slow accumulation of experiences that turns a person into themselves. I think about the things I'll never do, the person I'll never become.

  Then I think about what's coming. The seizures. The dementia. The long decline into something less than human. Months of watching myself disappear, piece by piece, while the people who love me watch helplessly. I can feel it reaching up my back like a tarantula, hairy and about to bite. I almost consider raging at the unfairness of all of it.

  I rage at the unfairness of it. I smash a couple of rocks against each other, beat my fists raw against the trees, and yell a little bit in a way that I'm sure will create new local cryptid legends. It takes a couple of hours to get it all out. Nobody wants to be born, enter the rat race, and then just drop dead. I had shit to do. By the time I'm done I'm bruised in several new, interesting places, my breath is haggard and bloody, and the skin on several parts of my body has been split open raw from where I've been throwing things, hitting things, you know, catharsis of that nature.

  It doesn't make me feel any better, but it makes me feel more alive. I go home and get ready to start disinfecting everything. I'm not gonna let sepsis get me before the suffocation does.

  On day twelve, I go back to the cave.

  I bring a flashlight. A blanket. A bottle of water, though I'm not sure why - habit, maybe, or some lingering survival instinct that hasn't caught up with my intentions.

  The entrance is just as I remember it. The air is just as wrong. I turn on the flashlight and make my way inside, crouching low where the ceiling drops, feeling the atmosphere shift around me as I descend.

  The back of the cave is a small chamber, maybe ten feet across. The floor is dirt and loose rock. The walls are damp. There's no light except what I brought with me.

  I spread out the blanket. Sit down. Turn off the flashlight.

  The darkness is complete. I can't see my hand in front of my face. All I can hear is my own breathing, and even that seems muffled, distant, like it belongs to someone else.

  The air is thick. Sweet. Already, something noxious is replacing the oxygen in my lungs.

  Have I made my peace? No. But it'll be better than the alternative.

  I close my eyes and go to sleep.