This Week on Mystery Theatre: The Case of the Rotating Portrait

You study the girl in the portrait, her face askance, as if she is in the process of turning away from the viewer. Her skin is smooth, neck slender and adorned with a ribbon, head high and capped with a bonnet. You fix your gaze, study her until, in a blink, the portrait changes. The slender neck vanishes, and the ribbon that adorned it has become the thin-lipped grin of a face that now appears to be turning toward you. And the skin—no longer flawlessly smooth—appears wrinkled and creased.

In t...