Line of Duty series 5, episode 2 review: Jed Mercurio's zigzagging plot can leave you feeling dim

A blizzard of acronyms continues to swirl and rage as Line of Duty (BBC1) plunges deeper into Jed Mercurio’s nightmare world of paranoia, betrayal and indecipherable police jargon. The (mostly) upstanding detectives from the AC-12 anti-corruption unit are on the tail of the OCG that liberated the contraband ED905 – and sometimes it’s confusing as all HELL.

Yet amid the alphabetti spaghetti of good guys, crooks and MacGuffins are several heart-thumping reveals and much satisfying murkiness as series five of the BBC’s conspiracy juggernaut stretches its legs. The latest in a distinguished parade of Line of Duty anti-heroes is confirmed to be UCO John Corbett (Stephen Graham). He’s an undercover operative apparently gone over to the dark side infiltrating an especially ruthless OCG (“organised crime group”, obviously).

That’s until he reveals to AC-12’s Steve Arnott (Martin Compston), whom he temporarily cuffs to his car, that he’s actually just pretending to have jumped off the deep end in order to evade the corrupt higher-ups determined to see him fail. By this point, Arnott and the rest of AC-12 have already cracked open the juicy particulars of Corbett’s secret posting and interrogated his apparently disillusioned wife (hilariously the mission has the Partridge-ian designation Operation Pear Tree).

But there’s just one letter that really matters and that is “H” – the alias of the evil copper behind the criminal plot squatting like a black heart at the centre of the force. Such is Corbett’s theory, anyway, as he confesses to Arnott. He warns the AC-12 man to trust none of his superiors – not even his seemingly upstanding commanding officer Ted Hastings (Adrian Dunbar).

Even the slowest of us – and Mercurio’s zigzagging plot can leave you feeling mightily dim – will have worked out that “H” is the first letter of Hastings. That isn’t the only clue the stoic superintendent might be up to no good.

His marriage has disintegrated after a property investment turned sour. And did you see the look Hastings threw as Arnott and DI Kate Fleming (Vicky McClure) asked compromised policewoman Jane Cafferty (Sian Reese-Williams) to identify the police bigwig who brought her into the conspiracy? If Hastings had a moustache it would be twirling so furiously that he’d be levitating inches above the floor.

Fleming and Arnott are also dealing with the fallout from the gangland execution of their turncoat colleague PC Maneet Bindra (Maya Sondhi). She has been bumped off by Corbett’s crew, having tried to make amends for her low-level betrayal of her fellow officers by spying on the criminals. Did Hastings and company accidentally push her too far? Or is AC-12’s senior detective a puppet master manipulating the psychological levers so that the naive Bindra would place herself in a hazardous position (and would it help if I drew a diagram?)

As with Mercurio’s 2018 mega-hit Bodyguard, this is dense, pacy fun. And, again like Bodyguard, the last thing you should do is take a moment and coldly scrutinise the storyline. Everyone is betraying everyone else and crooked coppers are sprouting like mushrooms in a landfill. Even the survivor from episode one’s drive-by raid, the aforementioned Cafferty, is on the take – blackmailed over an extramarital assignation in a car park (the grubby minutiae are another Mercurio touch).

No, Line of Duty has always been best enjoyed by going with the flow and pretending you can’t see the plot holes. For instance, it would be preposterous to suddenly make Hastings the bad guy five seasons in. And it indeed pushes credulity to portray Corbett as an honest cop killing and stealing in order to complete his ultimate mission of unmasking high-level corruption.

But what a romp it is. And, with Hastings in the frame as potential uber-villain and Arnott keeping his association with Corbett from Fleming, there are clearly many further bends in the road ahead. Line of Duty has never walked straight and this year is proving as thrillingly wonky as ever.