The Wire is a pretty unusual TV show in the end because it offers an antihumanist perspective on the potential of its characters. It features a huge number of charismatic, sympathetic characters ranging from senior politicians through the judiciary and police down to street kids, but it doesn't pretend that any of these characters can rise to manifest destiny.
Instead it's all about how the aggregated effects of their individually rational choices, within the complex of systems that makes up Baltimore society, are still often heartbreaking. So it's a great exposition of the idea that good people go wrong in a bad system.
Each season focuses on different organs of Baltimore—for example the drug trade on the "projects", the docks and the stevedores' union, the education system and child protection services, and the local newspaper. The cast of cops ties it all together. I wouldn't say it's "realistic" exactly because there are some blatant character fantasies, but you get the impression it's fairly meticulously researched (the show's creator was a police reporter at the Baltimore Sun for 13 years).
It has loads of great touches like the local actors some of whom were pulled off the same streets it's filmed on Ken Loach style, the ad libs, and the diegetic music. It's a top show.
