Teresa swallowed.

“Last night,” she said, “Miss Vanessa went into the study and unplugged the box for the cameras.

She thought it stopped everything from recording.

She said so.” I took out my phone and opened the security application, and I watched Vanessa watch me do it, and I saw in her face the dawning understanding that the ground she had been standing on so confidently had never been solid at all.

I want to be clear about what those cameras were and were not, because I have thought about it since.