Lost : a novel / Alice Lichtenstein.

Enhanced descriptions from Syndetics:

On a cold January morning Susan leaves her husband alone for a few minutes and returns to find him gone. Suffering from dementia, no longer able to dress or feed or wash himself, he has wandered alone into a frigid landscape with no sense of home or direction. Lost. Over the course of one weekend, the massive search for her husband brings Susan together with Jeff, a search and rescue expert and social worker preoccupied with his young wife's betrayal. In Jeff's care is Corey, a mute eleven-year-old boy who has been abandoned by his family after accidentally setting a tragic fire. As the temperature drops and the search and rescue effort threatens to become one of search and recovery, they each confront haunting memories and difficult choices that will have an unexpected impact on their collective future. From the intersection of these three lives emerges an arresting portrait of the shifting terrain of marriage and the devastating effects of physical and psychological damage. Written in spare, beautiful prose, Lost explores the lengths we will go to take care of someone and the ways in which responsibility, love, and sorrow can bind people together.