“What’s the matter?”

“I want to be sure she can’t hear us.”

“She? Nanny?”

Mary came toward him. “Tom, I woke up last night again. Because of the sounds. I heard them again, the same sounds, the sounds I heard before. And you told me it didn’t mean anything!”

Tom gestured. “It doesn’t. What does it mean?”

“I don’t know. That’s what worries me. But after we’re all asleep she comes downstairs. She leaves their room. She slips down the stairs as quietly as she can, as soon as she’s sure we’re all asleep.”

“But why?”

“I don’t know! Last night I heard her going down, slithering down the stairs, as quiet as a mouse. I heard her moving around down here. And then—”

“Then what?”

“Tom, then I heard her go out the back door. Out, outside the house. She went into the back yard. That was all I heard for awhile.”

Tom rubbed his jaw. “Go on.”

“I listened. I sat up in bed. You were asleep, of course. Sound asleep. No use trying to wake you. I got up and went to the window. I lifted the shade and looked out. She was out there, out in the back yard.”

“What was she doing?”

“I don’t know.” Mary Fields’s face was lined with worry. “I don’t know! What in the world would a Nanny be doing outside at night, in the back yard?”

It was dark. Terribly dark. But the infrared filter clicked into place, and the darkness vanished. The metal shape moved forward, easing through the kitchen, its treads half-retracted for greatest quiet. It came to the back door and halted, listening.

There was no sound. The house was still. They were all asleep upstairs. Sound asleep.

The Nanny pushed, and the back door opened. It moved out onto the porch, letting the door close gently behind it. The night air was thin and cold. And full of smells, all the strange, tingling smells of the night, when spring has begun to change into summer, when the ground is still moist and the hot July sun has not had a chance to kill all the little growing things.