A few hundred yards farther on, Dani veered to the right, off the gravel track and into the open space of the cornfield.

“Only step between the planted rows,” she whispered, “where the ground is packed hard. If you step where it’s soft you’ll leave prints.”

He saw what she meant; the distant mercury light was just bright enough to give away the denser soil between the corn shoots. He felt exposed out on the open ground, though he knew nobody watching from the house could see them. In daylight it would’ve been a different story. It would’ve been impossible for someone not to see them.

They followed a diagonal path across the field for two hundred feet and then Dani stopped. They were now very far from the road and the house, way out in the empty darkness of the cornfield. At first Sam couldn’t tell why Dani had stopped here. Then he leaned to the side and saw what was in front of her.

At a glance it was only a cluster of weeds and tangled shrubs. A little island of untended ground, ringed by big rocks that had probably been cleared from these fields a century and a half ago. The whole formation wasn’t much bigger than Sam’s bedroom.

But there was more to it. There was a shape hidden within the undergrowth, Sam saw. It looked like a dark rectangle lying flat among the weeds. He stepped up beside Dani for a closer look, and realized the big rectangle was actually a hole in the ground. In fact it was a staircase, leading down below the surface of the field.

“What the hell?” Sam said.

“Lauren and I first saw this the day we staked out the farmhouse. From the road, you could drive past this field every day, your whole life, and not know this was anything more than a patch of weeds. But from up in the trees, you can just make out the opening. We took a closer look at it that same night.”

“Where do the stairs go?” Sam asked.

“To the place you need to see to believe. Come on.”

Dani moved forward and set her foot carefully down onto the first step. Then she descended easily into the darkness. Sam followed. As soon as he was below the surface, he could see nothing at all. He made his way down the stairs by feel, running one hand along the wall—it felt like rough, cold concrete—to keep his balance. He’d gone down about twenty steps when he heard Dani’s voice, just ahead and below, telling him to be careful, and then he felt her hand reach up and take hold of his wrist.

“I’m at the bottom,” she said. “Take the last few steps slow, or you’ll walk into the door.”