They had performed for a camera.

I want to be honest about that camera, and about the safe, and about all of it, because I think there is a temptation to hear this story and conclude that I was simply lucky — that by some fortunate accident I happened to have installed surveillance in the exact room they happened to lock me in.

It was not luck.

It was the last, hardest gift my grandmother ever gave me, arriving years after her death, and it was this: she taught me to believe my own instincts even when the people around me were telling me I was paranoid.

When I found those tax documents two weeks earlier and felt the alarm go off in my chest, every reasonable, agreeable, marriage-preserving impulse in me said the same thing my husband would later say out loud — that I was imagining it, overreacting, seeing shadows.

The easy thing, the socially rewarded thing, the thing that keeps a marriage comfortable, would have been to talk myself out of it.