“Charlie,” John said patiently, and she tried to focus on him; she could feel her attention waning, as if her mind were spreading thin, floating out like clouds. “The faces,” John went on. “There was an earpiece so they could recognize you, right?”

She nodded.

“Could you make it work the other way?”

Charlie thought for a moment then met his eyes again. “You mean, make it so that the animatronics can’t see you?” She frowned, her focus returning as she concentrated on the problem. “The earpieces emit a frequency that alerts the animatronics to you, it makes you visible. If you inverted that frequency …” She paused again. “I don’t know if it would work, John. It might.”

“It could make us invisible to them?”

“Maybe, but that’s a big leap.”

“How would I do it? Invert the frequency?”

Charlie shrugged. “Just switch the wires, and …”

“Charlie, what part of ‘stay in bed’ wasn’t clear?” Marla asked good-naturedly, coming over to them. John stood, his mouth hanging open as though Marla had interrupted Charlie’s answer, but she didn’t seem poised to add more.

“Sorry,” he said hastily.

“Be careful,” Charlie said. She was beginning to feel light-headed again, and when Marla reached out to help her back to the bedroom, she did not protest.

*  *  *

John paused in the door, watching as Charlie curled up on her side, her eyes already closed. Marla raised her eyebrows, and he left, shutting the door halfway. In the living room, Carlton was kneeling beside Ella—now in doll form again—and looking intently into her ear.

“Uh, Carlton?” John said dubiously, and Carlton sat back on his heels.

“Amazing,” he said. “She looked human, like actually, for real, a human child.”

“Yeah, I think that was the idea. Can we talk outside?” John asked brusquely, and Carlton looked at him in surprise.

“Sure,” Carlton said with some concern in his voice.

“Come on.” John headed for the door, and Carlton hurried after him. Once they were outside, John looked at Carlton for a moment, thinking.

“What’s the idea?” Carlton asked with a hint of suspicion.

“Let me try to get this straight in my own head first,” John said. “Last year, when she was still in school, Charlie had this experiment she was doing, something about teaching robots language.”

“Oh yeah!” Carlton nodded enthusiastically. “She told me about it. Natural language programming. They listen to people talking around them, and to them, and they learn to talk, too. Didn’t sound like it worked very well, though.”

“Well, whatever. She had these earpieces—like, the robots would only talk to each other—they only recognized each other. You with me so far?”

“Um, I think?”

“Well, if you, Carlton, wanted to be in on the conversation, you would need to wear a special earpiece. The earpieces would make them recognize you. Otherwise, you were just part of the background, like they couldn’t see you.”