John spots the off ramp at ten past four in the afternoon. That is the time his watch says even if it looks more like twilight verging on night. Volcanic ash sifts down, gently, like a snow storm, except the sky is too dark for snow. He wonders what the sky looks like in Utah and Colorado.

He skirts around a car abandoned in the slow lane where it finally stalled after the ash choked its air filter. It's been there at least a day and a foot of ash has softened its shape. Cars litter the highway. He thinks of them as dead mammoths, their knees buckled and their heads bowed for the last time, as the ash fall slowly entombs them.

He plows through the grey powder down the off ramp. It is worse than walking in snow or sand, and twice as tiring. Squinting, he can just make out the large rectangular buildings ahead and he hopes the power is still on here. Gas stations and garages, fast food restaurants... the terms are already outdated. Now they are pitiful way stations, a place to simply get out of the ash, take off the dust mask, and breath for awhile. A place to sleep.

The backpack's straps weigh heavily across his shoulders. He is ready to stop for the day. Highway Five - it was boring at seventy-five miles per hour. At two, it is inescapable, interminable. He has spent the last two nights in deserted vehicles. He has had to search for ones left unlocked. It amazes him -- the world is ending and people still lock cars they will never see again. Is it out of habit or optimism? Maybe they have not heard the radio reports yet. Maybe they have heard and not believed. He finds the figures incomprehensible himself, but those radio announcers... he cannot dispute the grimness of their voices. The supervolcano had blown a hole fifty by thirty by one mile deep. Once, he'd visited the Meteorite Crater in Arizona and he had thought that was big. That hole in the ground was a mere pimple on the face of the giant caldera that had blown Yellowstone National Park and everything around it off the map and into the atmosphere.

The first building is a gas station: five rows of pumps and a mini-mart attached to a service garage. No lights shine from the forsaken building and he quashes his disappointment. The nights are so utterly black now. He longs for bright lights and cd players and microwave ovens.

The mini-mart's front door is unlocked and the ash accumulation has been swept away by the swinging of the door. John is not surprised. Many people on the road are on foot now, as he is, heading south for Mexico and beyond. He opens the door and ducks inside. He slips the dust mask off his face, takes a deep breath, and lets it out slowly enjoying the feel of clean air in his lungs again.

Voices come from his left and he follows the sound to a side door that opens onto the garage. A young family of four is gathered around a battery-powered camp light. They pause as he comes in and he quickly says, "Hi," and holds up his hands, palms out.

The husband and the wife eye him warily, the two children -- a boy and a younger girl -- fall silent. He doesn't blame them. Looters and thieves and worse stalk the road, and he is a big imposing man. "Name's John Hadley," he says. "Mind if I take a corner for the night?"

The husband shakes his head, and John walks over to the wall, tosses his hat down, and shrugs out of his backpack. It hits the ground with a thud.

"I should have thought of that," the husband says. John looks at him, and the husband gestures at the backpack.

"Here," the wife says. She's in her late twenties, he guesses. Petite, brown eyes, good figure, exhausted, terrified and trying not to show it. He wonders how long they've been on foot. She walks to him and offers him a moist towelette. "Your face," she says, and he rubs at his forehead. His hand comes away streaked with grey ash. He smiles ruefully and uses the proffered wipe to clean himself up. The tiny square is filthy before he's even half done but he persists, wiping away ash and grime.

The family is from Oakland, he learns. Tom, Jenny, and kids Jason and Lizzie. John looks at them and wonders how they can possibly survive. They have one day pack and nine plastic grocery bags, mostly holding food and water. At least their priorities are straight. They've left their collections behind. John wonders if that's a prerequisite of civilization, that need to collect nonessentials -- music, movies, books, videos, stamps, teddy bears, rocks. What a treasure trove it will be to future anthropologists when they finally unbury North America.

John joins them around their camp light and they share a meal of crackers and turkey jerky and chocolate bars taken from the mini-market's nearly depleted shelves. The kids, ages seven and five, fall asleep on their dirty blanket almost before they're done eating.

"You're marooned on a desert island and can only take one book -- which one do you grab?" John asks. "How come no one answers a 'Survival Guide' or '100 Ways to Build a Fire.' They always pick their favorite novel. As if it's all lounging in the shade of a palm tree drinking coconut milk."

Jenny says, "I wish we'd lived in Denver. Then it'd be over already. They're the lucky ones, you know."

John hides a shudder and looks at Tom. "You heading for Mexico?"

Tom nods.

"They said on the radio Mexico closed its borders and were shooting people on sight," John says. "But that might just be wild rumors."

Tom shakes his head, "I wouldn't blame them if they were. What the hell are they going to do with millions of homeless Americans? They don't have the resources to support themselves, let alone all of us. You know the National Guard was out in the Bay Area, trying to keep people from panicking and running. Stay at home? For what? Food and supplies can't come through by road with this ash clogging everything. Planes can't fly. The power's out and that means no water.... And people are packed in like sardines in the Bay Area. They can last days on what they've got right now, but months? Longer?"

Softly, her eyes never leaving her sleeping children, Jenny says, "We heard a guy on the radio... the eruption will cause a nuclear winter all over the world, not just here. Mass extinction of animals, crop failure, starvation, disease."

John says, "I was listening to some scientist guy talk about supervolcanoes. The last one that erupted -- Tuba? Toba? Something like that anyway -- seventy five thousand years ago... approximately ten thousand people survived. That's it."

Jenny's eyes well up with sudden tears and John wishes he had kept his mouth shut. She sits there, hunched forward, frayed and unraveling before his eyes. Her husband puts a hand on her shoulder, but she doesn't seem to react. John looks away from them. He has no comforting words to offer.

That night, John huddles in his sleeping bag in the corner of the service station, unable to sleep. He jumps as Jenny's voice come out of the darkness near his shoulder, "The children will not make it. It's over five hundred miles to the Mexican border and there's no guarantee of safety once we get there." Her voice is barely above a whisper.

"Kids are hardy," John says, matching her low tone.

He senses her shaking her head. "Not this time. I want to ask you for a favor."

Silently, he waits. She clicks on a tiny penlight that she has hidden under a cloth. A vague glow brightens up the space between them. He sees her gaze dart towards the forms of her sleeping husband and children, then she picks something up from the floor where she kneels beside him. He sucks in a breath -- it is a handgun. But she is not aiming it at him, she is holding it with both hands, one on the butt, one around the muzzle, offering it to him.

"No," he says hoarsely.

"Please. Tonight, while we sleep. All of us. There's money in Tom's pack. It's only six hundred dollars, but it's all we could get from the ATM machines before the power went out. It's yours."

"I don't want your money," John says. "Go back to sleep."

"They don't want to keep their masks on when we're outside. Do you know what will happen to them if they keep breathing in the ash particles? They can't walk all the way to Mexico, and we can't carry them the whole way. Please, please, just end this nightmare for us."

"I can't!" he says, and he has to consciously force his voice back down to an undertone. "Lady... Jenny. Just go away. You can't ask me to do this."

She wilts, sinking back. The flashlight glow paints shadows on her cheeks, makes her eyes dark sightless holes. "It would be humane," she whispers.

"It would be murder."

She bows her head, and her shoulders shake with mute sobs. She clutches the gun to her chest. "I'm sorry," she says and stands quickly, taking her penlight and gun with her.

John lets out a breath and listens to the rustles and murmurs as she returns to the blankets beside her husband. He holds his hands up before his face in the gloom. He can't see them, but he can feel them trembling.

He waits in the darkness until long after she stops tossing, until he can hear only steady breathing from where they sleep, then he laces on his boots and stands. He carefully pulls on his jacket and switches on his own flashlight in his pocket. The light barely escapes the material, but it is enough for him to see by. He lifts his backpack and carries it across to where the family sleeps and sets it down with a faint jingle of straps and plastic buckles next to their own bags of supplies. He hovers there a moment, but they do not stir. He returns to collect his sleeping bag. He carries it carefully, like a limp body in his arms, trying to minimize the slithering sound of the material as he lays it down near their feet.

For a moment, he watches them, but in the dim lighting they remind him too much of the abandoned vehicles on the highway. Instead of ash, blankets and coats bury them, but the end result is the same. He looks away. The sleeping bag might keep the kids warm at night as the temperature keeps dropping, and in his pack are six thousand dollars in small bills. It's not much, but it might buy them shelter or food or water, when it becomes necessary to pay for such things. If they make it to the border, money might get them into Mexico alive. Then, maybe, Jenny might hold her kids and smile again.

He backs away from them into the mini-mart. Here, he pulls the flashlight out of his pocket and gathers up candy bars, two bags of chips, and a package of beef jerky hiding on a bottom shelf and tosses them into a plastic grocery bag he finds under the counter.

He settles his hat low on his head and pushes out the front door into the black night.