"Every show must have a second, deeper layer of conflict underneath the surface level.  This gives the show depth and meaning.  It's also what keeps it going when other shows with similar surface conflict have bitten the dust." So, basically, "theme" is the driving force behind the program.  The thing that makes us tune in week after week.  And, if you ask me, Life on Mars has plenty of it. At its core, Life on Mars is essentially a police procedural.  The surface conflict, week after week, comes from the cases facing the detectives at Manchester CID, and the different approaches taken by Sam Tyler and Gene Hunt.  These are our two central characters: both strong-willed men with a passion for justice, but with conflicting opinions about rules and whether they should be followed. Under the surface, however, it's a show about fitting in.  Sam Tyler is a fish out of water, learning to adapt in a world that is foreign to him.  He's not even entirely sure whether he wants to be there.  And everyone that he meets thinks that he's a bit weird -- he talks about things that haven't even been invented yet, and claims that he's from the future.  How are the folks at CID supposed to work with a raving lunatic?  And how can Sam convince them that he's not completely mad?  Now, the problem with this, according to what I was taught today, is that this is a conflict that will eventually be resolved.