Childhood Sweetheart?

Karen and Greg were childhood sweethearts. Twelve-year-old Karen mysteriously disappears on her way to Greg's house. Seventeen years later, a woman claiming to be Karen shows up outside Greg's window. She tells Greg that she was abducted by a man who kept her prisoner for years. Greg and Karen's mother are convinced that this woman is Karen. However, Karen's father and the police detective who has been searching for Karen all these years have their doubts.