The sting, the burn, of hard exercise, the doubled excitement and fear of the unknown, kept me going for a long time. But, finally, I reached a point where fear overcame excitement. (You mean common sense overcame excitement.)

“Duncan!” I said finally, to his back. “We have to stop. We need to find our way home.”

He turned then, his hand on a tree trunk for support—a shadow framed by a greater gloom—and I’ll never forget what he said. He said, “There is no way to go but forward, Janice. If we go forward, we will find our way back.”

It sounded like something Dad would have said, not a nine-year-old kid.

“We’re already lost, Duncan. We have to go back.”

Duncan shook his head. “I’m not lost. I know where we are. We’re not there yet. I know something important lies ahead of us. I know it.”

“Duncan,” I said, “you’re wearing sandals. Your feet must be pretty badly cut up by now.”

“No,” he said, “I’m fine.” (I wasn’t fine. The brambles had lacerated my feet, but I’d decided to block out that discomfort because it was unimportant.)

“There’s something ahead of us,” he repeated.

“Yes, more forest,” I said. “It goes on for hundreds of miles.” I thought about whether I had the strength to carry a kicking, struggling Duncan all the way back to the house. Probably not.

I looked up, the long trunks of trees reaching toward a kaleidoscope of wheeling, dimly light-spackled upper branches, amid a welter of leaves. In those few places where the light was right, I could see, floating, spore and dust and strands of cobweb. Even the air between the trees was thick with the decay of life.

“Trust me,” Duncan said, and grinned. He headed off again, at such a speed that I had no choice but to follow him. In the shadows, my brother’s thin, wiry frame resembled more the thick, muscular body of a man. Was there any point at which I could convince him to stop, or would he stop on his own?

Another half hour or so—just as I could no longer identify our direction, so too I had begun to lose my sense of time—and a thick, suffocating panic had begun to overcome me. We were lost. We would never make it home. (You should have trusted me. You will need to trust me.)

But Duncan kept walking forward, into the unknown, the thick loam of the forest floor rising at times to his ankles.