The remarkable thing about the desert was the silence, not even a whisper of life, not anywhere. And then he heard it. It had been there all along, of course, but in the background. It was not something he focused on because everything else seemed more important, more urgent at a time of crisis.

Beneath the silence was a buzzing. It grew steadily louder and clearer, until it dominated everything. Finally it was as clear and as loud as if it were really there. A word came to him that he had never used, never even thought about: tinnitus.

The desert was nothing like what he had expected. He had had a picture in his mind of sinuous dunes and brilliant white expanses, of beauty. He hadn’t thought it would be all gray gravel and stones and crags and scrub bleeding into the barren brown ground. He hadn’t imagined the biggest desert in the world, all 4,000 miles of it, could be this ugly.

At first he thought, it’s only here, it’s only this place where I’m standing that’s so bare and lifeless and ugly. So he walked on with a spring of hope in his stride. His legs were not yet tired, his feet not yet sore, his skin still pale and cool.

The desert wasn’t supposed to be cold, but it was: winter, wind and night. It made him look forward to the dawn until he remembered what it would really be like, the heat of the day, the sun glaring from an unrelieved sky, not a shade for a hundred miles. He laughed at himself. He had a coat but no hat, no sunblock.

He wasn’t worried. He had half a gallon of water in a big canteen strapped to his shoulder, a compass, and the full moon as his guide. He knew Agadez, a city of more than 100,000 residents, lay due east. He had seen photos of its weird triangular minaret, an icon of the Sahara, towering above the low-rise city. He would see the Mosque of Agadez long before he walked into the ancient city, entered the narrow streets of the 600-year-old town, hemmed in by rows of low, flat-roofed adobe houses. They could have been copies of the tiny homes in 17th-century New Mexico villages.

He wanted to stand on one of those roofs beneath the full moon and look out at the minaret and the city and the desert beyond. That’s why they, he and his wife, had come here. As night approached, they had been in a hurry to pass through the ugly desert and get to Agadez. Too much of a hurry. That’s why they had made a choice to take the short cut dotted onto their sketch map.

Now all he had to do was keep walking east. How far? That was the only question.

His wife would not come with him, although he had argued with her, tried to insist. There was an oasis to the north and a road leading to it, and she would make for it. It’d be easier, also closer, she believed, although their crude map was not to scale. They each took a canteen. She had the map and he the compass. They shared the full moon. They didn’t kiss or hug or exchange endearments. It was not their way.

Good luck,” he said.

Until later,” she rejoined.

They waved and turned their backs and, like the veteran travelers they were, each set out determinedly on a camel track faintly visible in the night.

They had each chosen to go their own way all their lives together. It was their way, two stubborn, stable, able adults. Why change now? When one was rescued, he or she would send a search party for the other.

It gives us two chances instead of one, she argued, cogently as always. This was their choice, now as always.

It had been just one of those things that happened, the unexpected that travelers learn to accept as a byproduct of what they do, what they choose to do.

Their truck was passing through a field of razor-edged lava rock, some of it buried beneath shallow sand. When they collided with the unseen obstacle, two tires blew out at the same time.

They had a jack and a good spare. Only one.

Janet and William—never Jan and Bill, not even to each other—had come to the desert because they liked to explore the forgotten and lonely places. These kinds of places suited them. It was one of the few things they still had in common, one of the few things that kept them together these many decades. Lately, finding lonely and forgotten places had gotten harder. They’d finished with the easy ones, their destinations getting progressively tougher and meaner and more unforgiving. The Sahara was the hardest yet, forgiving no mistakes, none at all.

For 30 years they had traveled the world, but never before in the desert. For a couple in their 60s, they were in good shape, slender, strong and, they both thought, healthy. Tall and balding, he wore narrow glasses that gave him an owlish, professorial look that was not entirely misleading. At 61, she could, and still did, flirt when the mood came over her, occasionally. Tossing her thick grey mane or slowly crossing her legs, she could draw attention when she wanted. But they both knew there was more to her than that, much more.

His body wasn’t as good as it had been. Breathing was sometimes an effort. Knees stiffened. Fatigue gathered. Just keeping on became tough, as it was now, trudging on the rocky and gravelly plain under a cold moon throwing shifting shadows, and now the sounds becoming so loud in his head he could no longer think clearly.

He wondered if she heard the same sounds, shivered in the same cold, saw the same shadows, felt the same fatigue.

Wondering, he trudged on.