Strayed 2009

The main character, his wife and small son lose their way and become stuck on a country road. As a result, they have to spend the night in their car. The following morning, the main character awakens alone, his wife and son having mysteriously disappeared. His preliminary searches bring the hero to a small lonely house, in which an old man and a young woman live. It seems that these strange tenants know about him and his family but try to hide their knowledge. For what reason?