Unforgotten is everything that Line of Duty is not – understated, subtle and believable

Nobody will forget the final episode of Unforgotten season four in a hurry. Chris Lang’s cold case thriller drew down the shutters in wrenching fashion as DCI Cassie Stuart (Nicola Walker) succumbed to the life-threatening head injuries she had suffered in that car crash the previous week.

And yet the big twist was that there was no twist. At least not in the manner in which Stuart was wheeled off-stage. It had clearly been final curtains for her ever since a stolen SUV clattered into her vehicle seven days earlier. The show was honest with us to the end.

At least until Stuart's end - ITV has announced that Unforgotten will continue into a fifth series, with Sanjeev Bhaskar's DI Sunny Khan partnering up with a new detective. Whether the show, brilliant as it is, should continue without Walker is an argument for another day. Now is time to reflect on the achievements of a whodunnit which never tried to outfox the viewer and was more interested in the humanity of its characters than in convoluted plotting or death-by-acronym.

You can see where this is leading. Comparisons with Line of Duty are inevitable. And yet the gulf between the two blockbuster capers is vast. One is a celebration of cleverness for the sake of cleverness and of storylines that have the quality of a snake swallowing its tail.

And then there is Unforgotten, which pays the audience the compliment of never attempting to get one over on them or demanding they spend half their viewing time checking Wikipedia entries from previous seasons.

Take the final scene of last week's Line of Duty, in which a fleeting shot of a bearded man in a car had viewers scrambling to work out exactly who he was. Had we seen him before? Was he significant? Was he - bizarrely - Neil Morrissey? All of this soared over my head: without Twitter I wouldn’t have even suspected.

No such deep delving is required of Unforgotten, a drama with two feet firmly planted in the real world. The other great insight Lang brings is that people are comprised of varying shades of grey and are rarely black and white.

Who is the all-time top villain on Unforgotten? There really wasn’t one, was there? Certainly not this season, where four now middle-aged former police college classmates conspired to cover up the killing of a hoodlum.

The plot was rooted in ambivalence. Matthew Walsh, the victim, was a sexual predator and a lout. This was not to suggest he deserved his fate of death-by-fountain pen. Rather, it was Lang’s way of acknowledging the contradictions encountered in everyday life. Sometimes good things happen to bad people. Sometimes bad things happen to good people. And sometimes bad things happen to bad people. It’s just a roll of the dice.

The suspects were similarly neither heroic nor wicked. Dean Barton (Andy Nyman), the killer, had desperately wanted to escape the shadow of his criminal family. Ram Sidhu (Phaldut Sharma), his intemperate pal, had been shaped by society’s hardwired racism.

Fiona Grayson (Liz White) was another sort of victim: she had become a policewoman in response to pressure from her father. And Liz Baildon (Susan Lynch) was an overachiever dragged down by happenstance. Her crime was to be in the wrong place at the wrong time.

Contrast this with Line of Duty where baddies abound and where character development is closer to a Marvel movie than to classic British thriller tradition. That was confirmed by the absurd season five subplot in which upstanding Ted Hastings (Adrian Dunbar) was briefly dangled as the mega baddie. Suddenly, he went from jolly “haud your wisht” banter to ominous scowls and creepy padding about with a laptop under his arm.

Game of Thrones is the precedent here rather than the crime milieu to which Unforgotten belongs. In Line of Duty everyone speaks in arcane lingo – much as the Starks and Lannisters did – and there is little sense of a world beyond the “Here Be Coppers” realm of Jed Mercurio’s plotting. It’s fun – sometimes deliriously so. But it is very much its own self-contained thing.

Everyone is either a police officer, “bent” or otherwise, or somehow plugged into the shadowy wider conspiracy. Can you imagine, for instance, an exchange in Line of Duty similar to that in Unforgotten in which Sunny Khan challenges Stuart to recall the year in which Marathon bars were re-named Snickers? On Line of Duty it would probably be referred to as a “BRBOC” ("Bafflingly Renamed Bar of Chocolate") and we would be left to our own devices trying to tease out what they were banging on about.

“If I had to define the essential DNA of Unforgotten, it’s that good people can do bad things,” Lang told the Sunday Times recently. What he’s getting at is that the show stands as an acknowledgment of human decency and fallibility. Just as in real life, there are no heroes or villains – merely ordinary individuals muddling through. Perhaps that is where its power resides: it holds up a mirror to the audience and confronts us with the reflections gazing back.

Is Unforgotten better than Line of Duty? Let us know in the comments section below.