Are you watching this show? Why aren't you making every effort to watch this show? It's like the Battlestar Galactica - NEW VERSION - of police dramas. Or drug trade dramas. Or working the docks dramas. Or getting elected dramas. Or surviving going to school in the ghetto (box cutters oh god)!
Yes, this show really does require watching it from the beginning. Sure, you could get into it at the beginning of each season, just about - but watching it from the beginning is just SO rewarding. The characters that David Simon (of Homicide: Life on the Street fame) are so amazing. He gives a piece of humanity to everyone on the show, be them a flawed police, a lesbian, a homo thug, a crackhead, a hustler, a corner boy, a CODE BREAKER. It's just so amazing.
It's got one more season to go so check it out before you miss out on some amazing TV.