A 3:30 a.m. phone call is enough to make anyone's heart stop and blood run cold. However, Cindy Shell was not overly concerned when her father called in the middle of the night, asking her to check on her mother, who left him a garbled message an hour before and then didn't answer the phone. She knew there must be a rational explanation, so she unhurriedly drove the seven minutes to her parents' home to make sure everything was okay. But everything...