I've watched three seasons of The Wire on DVD so far, and the second season is my favorite.
It takes place on the docks, where the leader of the stevedore's union gets in over his head with a group of smugglers. The union leader is doing bad things with good intentions -- he's trying to save his men's jobs, but the criminals he gets involved with do things far worse than smuggling televisions.
The Wire is a complex show, and I suggest watching it from the beginning, not jumping in at season two, because even though season two's focus is different from season one's, there are some recurring characters and plot lines that are carried over. Also, in season three, some major plot lines are resolved, so it's good to have followed them from the start to get the complete story.