The Sleepwalker

 Fiction by Chris Bohjalian

https://www.barnesandnoble.com

Annalee Ahlberg is a chronic sleepwalker, and when she disappears from her room one night in August, it's assumed that she accidentally sleepwalked into a nearby river. Her daughters Lianna and Paige are hoping against hope that she will still come home, but then her body is finally found. But did Annalee actually walk into the river on her own?

This was a good-enough story, but it moved too slowly for me. Still, the ending was surprising.

I also read recently by this author: Close Your Eyes Hold Hands