I think the missing relates to the theory of uses and gratification because some people like watching these kind of TV series because they enjoy the mystery and trying to find out where the missing person has gone and how the lead up is and potentially finding the missing boy in France.

Escapism is something the viewers seek for because when you are watching a show that you are interested in, you want to know what is happening and eventually you get so intrigued that you will put yourself in their shoes.