I was not familiar with the case of Shanann Watts, her husband Chris, and their two children before seeing Jenny Popplewell’s documentary American Murder: The Family Next Door. To Popplewell’s immense credit, she is never exploitative about the case, instead using it as a way to frame how our online lives contrast against our private struggles, and how what may seem like the perfect family online is a thin veil for a tragic home life. With the word “Murder” in the title, the documentary isn’t really concerned with “whodunnit” or following various clues and threads. The grisly …