Line of Duty

What is Line of Duty about (plot, summary)
Line of Duty is a British BBC police procedural television series created by Jed Mercurio. The first series premiered on 26 June 2012 and became BBC Two's best-performing drama series in ten years with a consolidated audience of 4.1 million viewers.
A drama about the investigations of AC-12, a controversial Police Anti-Corruption Unit.