Line of Duty is a British cop show that follows the internal affairs unit as they attempt to flush out corruption in their own ranks. In the first series, Detective Sergeant Steve Arnott is transferred to the anti-corruption squad after he refuses to participate in the cover-up of a botched counter-terrorism raid. In his new position, he finds himself charged with looking into the possibly-shady activities of Detective Chief Inspector Gates, who has come to the attention of the anti-corruption unit because of his team's unusually high solve rate for their cases. Gates' unique success has brought him under suspicion of "laddering," or adding on additional charges to cases he already knows can be solved, artificially jacking up his team's percentage of cases closed successfully. When they start poking around, Arnott and his colleagues find out that Gates has much more to hide than manipulating his statistics. They just need to prove it.
I find this series to be well-written, well-acted, and quite suspenseful. I like that the cases--both the case against Gates and the failed counter-terrorism raid--are densely packed with details, and enough twists and dead-ends to build some real suspense. On the other hand, the show is not so dedicated to throwing out false leads that it becomes confusing or convoluted. I enjoyed the six-episode series enough to complete it in two sittings--and moved right on to the second series. The library owns the second and third series on DVD as well, and the fourth series, which just aired in the UK, should be following shortly.