I’ve just watched the final episode of the BBC drama series Line of Duty. My verdict? Six hours I won’t get back and I shan’t be eagerly awaiting the next series.

The story was harrowing and the telling of it was intense. It was gripping but the vice turned out to be despair, not hope. I don’t think it gives too much of the game away to suggest that every single character is compromised to some extent. Who watches the watchmen, and who watches those who watch the watchmen?

I was particularly disappointed by the ending. An extended flashback gave further insight into the story (and tarnished more reputations) but, back in the present, time had run out and the last few minutes became a montage of clips with overlaid subtitles about the fates of some of the key players. Convictions were made but truth was not revealed; the only saving grace was that the series only ran to six episodes rather than dragging it out further.

In contrast, Shetland: Raven Black (another visit by the BBC to Ann Cleeves’ world of police work in those remote islands) was much more to my taste. The themes are still dark and the ending is far from unsullied joy but at least Jimmy Perez is a policeman who seeks truth, upholds justice and acts with fairness. That’s what I want in the stories I watch or read; heroes who stand firm in the line of duty.