Black Mirror is an anthology show where a whole bunch of different stories take place. There's elements of horror, sci-fi, survival and others contained in 4, soon to be 5, seasons of 6 episodes each.

Each episode is self-contained in that they don't touch on any of the other episodes except in the most superficial way. For example in more than one episode they make reference to "brown suede" as a style of coffee. But there's no specific callbacks to any specific episode. It's more like these all take place within a shared universe.

There is a certain amount of darkness to it, after all it's not called "Black Mirror" for nothing. Social commentary is a thing and they use the show to reference this. Whether it's our addiction to things like Facebook, Instagram and how others see us all of these things are spoken of in one way or another.

I seriously tell anybody not to binge watch this as easy as it might be for you to do. Take the time to think about and digest the information and what the episode was trying to say and give yourself some time before firing up the next one.