Mean Streak by Sandra Brown

Mean Streak - Dr. Emory Charbonneau wakes up in a cabin in the woods of North Carolina with a head injury.  The man who resides in the cabin takes care of her, but refuses to tell her his name, and refuses to let her go or call anyone.  Emory's husband Jeff, who is having an affair, waits to report his wife missing, which indicates to the local police that he killed her.

At the cabin, Emory and the man encounter his neighbors who have nefarious intent towards the man.  The fracas involves a very sick young girl, that Emory takes care of, in spite of the girls older brothers.