I have a rule that says in order to determine if a TV show is good or not you need to see at least four episodes. That is about how long it takes for you to get into the characters, get a sense of where the show is going and what the creators want to tell you. I have been lucky enough to get a chance to see the first four episodes of Mr Mercedes and in this spoiler free review I’ll let you know if this is a show you need to see…