Line Of Duty: Every Series Ranked From Worst To Best
4. Season Five
Plot: AC-12 continue to investigate the mysterious Organised Crime Group and try to bring in John Corbett (Stephen Graham), an undercover officer who appears to have gone rogue.
Although this was the most-watched season of Line of Duty to date, this seems to have been considered a disappointment by some reviewers. It is true that this wasn't as good as the past three seasons, but season five was still absolutely excellent and that shouldn't be forgotten.
The characters make a few dumb decisions, the storyline of Kate Fleming and her husband is under-written, it doesn't have as many good set-pieces as other seasons and it's slow to start, but from episode three onwards it really picks up. Ultimately, this is another sublime combination of a heart-in-mouth thrill ride and powerful emotional drama.
Additionally, John Corbett is another tremendous investigative target who all viewers will care about deeply, meaning his tragic end is very hard to take.
The season culminates in a nail-biting 90-minute finale (which also features a scene-stealing, brilliantly unlikeable guest performance from Anna Maxwell Martin) in which the much-loved Superintendent Ted Hastings is accused of being H and is subjected to an unbearably tense interrogation.
Best Episode: Episode four.