Artwork by Scott Altmann

According to Jorge, sometime after we pass through Denver the California Zephyr will run out of diesel. Jorge's already decided that when the train stops, he will, too -- like a captain going down with the ship. He's got a wife and a passel of kids back in Chicago who he'll probably never see again, so I guess I understand.

Me, I plan to keep heading west with as many of the other passengers as care to go. Just keep on going till we drop dead of exhaustion or hit the Pacific or the darkness catches us.

We don't know for a fact that anyone back east is dead. Or alive, either. Some of the passengers just sit up in the dome car and watch the landscape behind us stretch like salt-water taffy as it reddens and finally fades into the blackness that follows us. Others are so freaked out they just sit in the dining car finishing off the liquor, free of charge. The rest of us sit in our regular seats, like everything's normal.

"Those scientists at CERN overdid it," says Varney. His t-shirt's a couple of Xs too small, but people listen to him because he's loud and confident. "They probably created the black hole."

I've already told him you don't escape a world-devouring black hole on Amtrak, but he's fixated on the idea because it's something he understands.

Me, I'm fixated on what I don't understand: when we pass through a town, everyone we see is frozen in place.

"Gravitationally induced time dilation" is Varney's answer. Makes no sense, 'cause we're just as close to the event horizon, so our time would be dilated, too.

A spindly woman with wiry red hair and librarian glasses sits down in the seat opposite me. "You think he's full of it."

I shake my head. "Not 'think.' I know he is."

"So, what's your theory?" Her voice is casual, like she's asking about tomorrow's weather, not the end of the world.

I shrug. "I thought the speed of light had slowed to 50 miles an hour or so. Fit with the red-shift out back and the time dilation as we passed things at a high fraction of the speed of light. Was a pleasant theory."

"Pleasant?" she asks.

"It would mean the rest of the world was still there behind us, if it was true. But it's not."

"Why not?"

"There's no blue shift ahead of us."

She nods as if she understands. Maybe she does -- she's smart enough to know Varney's wrong. She extends her right hand. "Dawn Rigby."

We shake hands as I say, "Carmichael Paxon. Friends call me Carpy."

"So what's your new theory, Carpy?"

"Don't have one that fits the data," I say. "Have a plan that fits the data, though: keep heading west, away from whatever's going on back there." I jerk a thumb over my shoulder.

Her eyes flicker to the window, then widen. I turn and see a dusty red pickup speeding along the highway running parallel to the tracks on our left. A man leans half out of the passenger side, waving a battered cowboy hat as if to flag us down. He's yelling something, but I can't hear him through the glass.

"So the rest of the world isn't frozen," says Dawn.

Some of Varney's audience notice the pickup, too, and pretty soon they're all at the windows, gawking at two men in a pickup like they're a couple of movie stars.

"We've got to stop for them," says Dawn.

Varney snorts. "You're crazy. The black hole will get us if we stop."

A murmur of agreement ripples through the other passengers.

I decide I've had enough, so I stand. "Look, folks, I don't know what that is back there, but it is definitely not a black hole."

"Why should they believe you and not me?" asks Varney, jutting his chin toward me. He's got three inches on me in height and he's close to double my weight, but most of that is fat. He can't really be looking for a fight -- he's probably just as scared as any of us.

So I play the authority card. "Because I used to be Marine Corps astronaut with the Shuttle program, that's why. I've forgotten more about space than you've ever learned, and I tell you, that's no black hole."

What I don't tell him is that I washed out of the space program. Kinda tough being an astronaut after you develop an irrational aversion to flying.

He stares at me for a moment, then heaves his shoulders in a massive shrug. "So it's not a black hole. Whatever it is, it's coming up behind us and we can't afford to stop."

"You don't know that," says Dawn. "We slowed down going through that town in Nebraska, and it didn't catch us."

Before Varney can respond, I say, "In the Marines, they taught me never leave a man behind." I jab a finger toward the pickup. "If they need a ride to escape what's coming, we'll give it to them. We clear?"

Varney swallows, then nods his head.

Jorge agrees to slow the train. I still can't hear the men in the pickup over the clatter of the train wheels, but I think I convey the plan to them well enough through gestures. They speed on ahead of us. Jorge says they should find a crossing in a few miles, and we'll have slowed down enough by then that they can climb aboard.

Dawn meets me before I get back to the rest of the passengers.

"Thank you," she says.

"Getting people focused on rescuing someone else was a good idea," I say. "Keeps them from panicking."

Her glasses have slid down her nose a bit, and she pushes them back up. "I didn't suggest it to keep people from panicking -- those men were in trouble and I wanted to help."

"There's that, too," I say, and I feel like I'm talking to Miriam again. She was always going out of her way to help people, right up to the end. After the plane crash she helped me to safety, and then went back to get someone else. I was too concussed to stop her.

Not wanting to think about Miriam any more, I push past Dawn and say over my shoulder, "We need to get people to open doors all along the train, just in case those guys miss the first one."

From my post at the last door on the train, I look back at the blackness to the east. Jorge has slowed the train down to about five miles an hour, but it seems the darkness has slowed as well. If anything, it looks farther behind us than it used to be.

A shout from the front of the train turns my attention forward. I spot the red pickup: they've turned off the highway onto a road that crosses the railway. For some reason, though, they're just sitting in the cab, still a good thirty yards away from the tracks. A cloud of dust kicked up by their tires still hangs in the air behind them, and it looks wrong.

Ahead of me on the train, people start calling out to the men, but I realize it won't do any good. We pass by the men, who are frozen in place.

"How terrible," says Dawn, as I meet up with her near the middle of the train. "They were so close to being safe with us."

"Safe is a relative term," I say.

She smiles. "You sure know how to comfort a lady. But I'm pretty sure the darkness is slowing, so I'm hopeful we'll outrun it and find a safe place."

I'm only half paying attention to her words, because the word relative is sparking connections in my brain. I had already discarded the idea of time dilation due to relativity, but relative motion did seem to matter.

Varney stands up from his seat. "It was a good try, man," he says. "Not your fault they froze."

"They weren't frozen when they were cruising down the highway parallel to us," I say, mostly to hear myself think. "But when they turned off the highway --"

The metal-on-metal screech of the brakes sounds again, and I realize Jorge is still slowing us, maybe even planning to stop.

"No!" I yell. I squeeze between a surprised Dawn and a protesting Varney, and sprint forward through the train cars. "Jorge, don't stop the train!"

I keep repeating that at the top of my lungs as I pass by the other passengers. Some are a little too slow to move out of my way and I shove them aside, not caring if I cause a few bruises on the way. I've got to get to the engine before we stop completely. No matter what, Jorge has to keep us going.

Because if I'm right, the moment we stop moving west it's all over.

I reach the engine compartment. "Keep going!"

Jorge looks back at me over his shoulder. "But those guys --"

"We can't help them," I say. "If we stop, we'll end up frozen like them."

After a moment's hesitation, he nods. "How fast should I go?"

"Whatever's most fuel efficient," I say. "Whatever keeps us going the longest."

About thirty passengers care enough to gather in one of the cars to listen to my theory.

"The pickup truck was doing just fine as it drove along the highway," I say. "But when it turned onto the road to cross the tracks, it froze. And that made me wonder what was different between the highway and the road."

"Speed," says Varney. "They dropped below some critical threshold and that caused them to freeze."

"It's like that movie with the bus," says a passenger near the back of the car.

"Speed," says Varney.

"No," I say, "It's not speed. It --"

"Yes, it was," says Varney. "Sandra Bullock and Keanu -- "

"I mean it's not speed that's important. It's direction." I point toward the front of the train. "As long as we're moving west, we're okay. The truck turned north when it got off the highway, so it wasn't moving west any more. That's why it froze."

"I'm not saying you're wrong," says Dawn, "but why should it make any difference which direction we're going?"

"I think we can all agree that something's gone wrong with the physics we're used to." Nobody objects, so I continue. "And everybody's probably heard about time being another dimension. Well, the simplified explanation for what I think's happened is that the time dimension has lined up with a space dimension." I point to the rear of the train. "That's the past . . ." I swing my arm toward the front of the train again. ". . . and that is the future. To keep moving through time, we have to keep moving west."

I hope that Varney won't argue with the simplified explanation, but he doesn't fail to disappoint.

"Why would going west --" he says.

"Look, I'll be happy to discuss the more technical aspects with anyone who wants," I say. "The point is as long as we're moving west, we're safe."

"What happens when the train runs out of fuel?" asks Dawn.

"We've got several hours before we'll have to cross that bridge," I say. "Till then, we just have to hope this wrinkle straightens itself out first."

Satisfied there's no immediate danger, most of the passengers disperse. Dawn and a handful of others stick around to hear me discuss General Relativity with Varney, and how Earth's rotation is dragging the partially collapsed local spacetime in an eastward direction, and how only by resisting that drag are we able to move through time.

"We've got a serious problem," says Varney quietly as he slides into the seat next to me.

"I know that," I say. We've evacuated all the passengers into the front two cars and disconnected the rest, although there was some grumbling about lost luggage. Jorge thinks we've dumped enough weight to get us to Salt Lake City without refueling. Once we get there, though, the problem is how to get fuel into the train without stopping. I haven't even started thinking about what happens when we run out of track.

"We can't get over the mountains," says Varney.

"I'm sure Jorge factored the mountains into his fuel calcul --" I say.

"No," says Varney, and he holds out a portable GPS mapping unit. "I've been looking at our route on this, and there are times when the track turns north, even a little bit east, as it goes through the mountains. When that happens, game over."

I take a moment to ponder the implications. "So we abandon the train, steal some cars, and find another route over the mountains."

Varney gives me a sour look. "Just because I was wrong about the black hole doesn't mean I'm stupid. I've checked the major roads. All of them wind around the wrong way at some point. And even in a Jeep, you can't just four-wheel across the Rockies."

I slump back. "So there's no way out."

"What do you mean?" Varney frowns at me. "Marine Corps astronaut -- doesn't that mean you were a test pilot? Let's grab a plane and fly!"

"I . . ." My stomach knots at the thought of flying, particularly over the same mountains where I'd crashed. I wrench my thoughts away from Miriam and say, "I was a pilot, yes. And you're right, it's our only option."

Near Fort Morgan, Jorge slows the train so we can hop off. Only twenty-one of us are brave enough to do so. The rest will continue on the train and hope for a miracle.

Even though Denver International Airport is about fifty miles southwest of us, as long as we have some westward motion, we'll keep moving forward in time. But while the fittest of us might somehow manage to walk the whole way without stopping, some -- like Varley -- definitely will not. We need to steal some vehicles.

Even with everyone eerily frozen around us, stealing a car is not simple. Unoccupied cars generally don't have keys in them, and none of us knows how to hotwire. Since we can't stop moving west, even for a moment, that rules out all cars not facing west. If a car were moving west, though, it would keep moving through time, which means we only have access to cars that are stopped, which means they're either parked or their brakes are on -- neither of which is helpful if you need to keep moving.

We end up stealing tractors instead of cars, because we find them in fields with the keys still in them. With a large group, pushing a small tractor to get it moving through time isn't all that hard. Once it's moving, the engine will start.

Eventually we have six tractors, led by one with a bulldozer blade, trundling across Colorado farmland.

Dawn is squeezed on the tractor seat beside me. I haven't been this close to a woman since Miriam died. She's staring up at the sky and I admire the smoothness of her neck. I yank my gaze away as she looks at me.

"There's something bothering you," she says. "Something you haven't told us."

"What makes you say that?" I ask.

"You tense up anytime someone mentions the plane."

Miriam had been annoyingly perceptive, too. "Stealing a plane that can carry all of us won't be as easy as stealing a tractor."

"Uh-huh," Dawn says. After moment, she adds, "Are you really a pilot?"

I let out a long breath. "Used to be. Last time I flew was three years ago, just me and my wife and some friends in a small plane, coming back from Vegas. The engine died, so I crash-landed our plane on a snow-covered slope in the Rockies. I was injured. My wife pulled me out of the plane and then went back inside for someone else. The plane slid down and off a cliff. They couldn't get to the bodies until spring. Since then, I haven't had the nerve to fly. Any more questions?"

I've found that being cold and blunt about what happened usually makes people shut up or change the subject. Dawn looks at me for a moment, then says, "You blame her, don't you?"

"What?" I feel sudden anger at Dawn for daring to continue talking about it.

"For leaving you and going back in the plane." Dawn's voice is matter-of-fact. "You blame her for dying."

I hop off the tractor to walk alongside. Dawn takes over steering, but she doesn't say anything.

The wind blows in from the east and off into the west. After a few minutes, it chills my anger, and I climb onto the tractor again and squeeze onto the seat next to Dawn. Our hands touch as I take over the wheel.

Denver International Airport is no good. All the parked planes are west of the runways. So we keep going southwest, to Centennial airport in Highlands Ranch.

There we get lucky, and find a Beechcraft 1900 east of the runway. It's a twin-prop plane with room for nineteen passengers, and with careful coordination of ropes attached to slow-moving tractors, we start moving it west. And while I may not know how to hot-wire a car, I can hotwire a plane.

Dawn sits with me up front. She squeezes my hand and says, "I'm here for you."

I throttle up and we accelerate down the runway. I don't like the fact that we're taking off with the wind rather than into it, but there's no choice.

And that's the thought that gets me through the panic as we take off. There's no choice -- I have to do this.

And I do.

The strong tailwind extends our range, but eventually I don't want to push our luck too far and take us down when fuel starts getting low. We land without incident, on I-15 about 40 miles north of Cedar City, Utah. The southbound lanes are clear of cars because the Interstate is really headed more southwest than south, so any cars that had been on this stretch would have kept going forward.

I keep the plane rolling while everyone else climbs out, then I follow.

"Everyone keep an eye out for tractors," I say, setting an easy walking pace. No need to wear anyone out.

Dawn takes my hand as we trudge along the highway. I don't pull away.

Less than five miles down the road, we lose someone: Jana McFarren, a fifty-five-year-old grandmother who'd been visiting her grandkids in Chicago. She's at the back of our group when she exclaims, "Oh!"

It's the last thing she says.

I look back over my shoulder in time to see her toppling forward, arms stretched out to break her fall. She hits the ground and just stops, frozen in time.

Next to me, Dawn slows and turns to see what's happened. I grab her arm and keep pulling her forward.

"We have to help her," says Dawn, struggling against my grip.

"We can't," I remind her. "We can't go back for anyone."

She stops resisting, and the twenty of us continue in silence.

Except for Varney, who sidles up to me and says, "Leave no man behind, huh?"

"Shut up," I say. After a moment, I add, "You take the lead. I'll bring up the rear, just in case." I slow down to let everyone else pass me.

Through various stolen methods of transportation, we travel steadily west. All the while, we try to figure out what to do when we reach the Pacific.

Jana's the only one we lose by accident. Five people just decide to stop and hope everything unfreezes on its own eventually.

A couple miles past Barstow, Varney figures out why a sailboat is the perfect solution. "The wind can't blow to the east," he says. "It would stop in time. Therefore, the air has no choice but to move west. That's why the wind blows constantly to the west."

That's when we start planning to steal a large sailboat once we reach the Pacific.

We're at Oceanside Harbor. I kiss Dawn for luck, and then she and the rest run on ahead. Their role is to cut the ropes holding our target sailboat to the dock and then clamber aboard and try to unfurl as much sail as possible while moving toward the bow of the boat, to the west.

My job is to plunge our commandeered Greyhound bus into the water just behind the boat, causing a shock wave to give the boat enough forward momentum that we'll have more time to get the sails out.

Once I see everyone's close enough to the boat, I gun the Greyhound's motor and aim it at the right spot behind the boat. Just as I jump out to run to catch the boat, the bus jolts as it hits something. I manage to hit the dock running, but I'm off balance.

The bus slides into the water as planned, and a surge pushes the sailboat westward.

As I fall, I see the sailboat pulling away, speeding up even as I slow down. I find comfort in the fact that I will freeze forever watching Dawn and the others sail away into the west. My final duty is done.

I come to a stop --

Then the boat disappears and my arms feel like they're being yanked out of their sockets. I'm being dragged along the dock.

"Got him!" It's Varney's voice.

I twist my neck to see who's pulling me. A tall, muscular man with a thinner version of Varney's face has my right arm. And pulling my left arm is Dawn -- hair cropped short, skin deeply tanned, glasses gone, but definitely Dawn.

They help me to my feet and we continue running toward the end of the dock. A powerboat putters slowly alongside, with someone I don't recognize at the helm.

"Jump in," says Dawn, and I do. She and Varney join me. The boat speeds up.

My mind finally catches up with the fact that I'm not frozen. "How?" I ask. "How'd you manage to come back for me?"

"We didn't," says Varney. "Going back's impossible."

"We kept going west," Dawn says. "Eventually, that brought us back here, and that gave us the chance to pick you up."

"But . . ." I look at the interior of the powerboat. "You've got no supplies, and this boat will run out of fuel."

"Relax. We're going to meet the flotilla." Varney smiles as he leans back in his seat. "We've got 836 people now -- 837, including you -- and if today's operations went well, over 50 sailboats. We've got it under control. And wait till you hear about our plan to rescue a nuclear-powered aircraft carrier that's frozen near Hawaii."

Obviously, a lot has changed while I was frozen. I look at Dawn sitting beside me, and I wonder if her feelings have changed, too.

Dawn must have sensed my apprehension, because she leans into me. "Don't ever make me leave you behind again," she says.

We kiss as the boat continues into the west.