Utopia is a six part series that was broadcast on the UK's Channel 4 in early 2013. I have only just found it. It is the best thing I have seen for a long time. Superb acting. Very violent.
The Wikipedia article is here.
Utopia is available on DVD and as a torrent.
A second series starts on Channel 4 next week. HBO are doing an American version.
Another series worth seeing is Rubicon. This will be harder to find since, strangely enough, it was only shown once and is not available on DVD. It is barely available as a torrent.