When I came home from deployment, my wife told the neighbors, “His mother has dementia—she hurts herself.” But I found Mom locked in a dark bedroom, fully lucid, with no phone and b:ruis she refused to explain. I smiled, pretended to believe my wife, and secretly recorded her boasting, “No one will trust that old woman.” The next morning, I drove her to the psychiatric evaluation she had arranged for Mom—and handed the doctor a different file.

The moment my boots hit the pavement outside the taxi, the first thing I heard was my wife speaking to Mrs. Smith regarding my mother’s supposed cognitive decline. The second…