Line Of Duty joins War And Peace, The Night Manager, Happy Valley, and The A Word as the latest BBC drama battling for the BAFTAs, by Jim Shelley 

The good news was that Line Of Duty was great television.

On the down side its portrayal of the police was so eerily convincing it left you feeling more uneasy than entertained.

That noise viewers could probably hear was Dixon Of Dock Green turning in his grave.

The heart-warming tales of the Bobby on the beat have been left behind in the 1950s, 60s and in Heartbeat, replaced by Line Of Duty's relentlessly grim, seemingly realistic, investigations into police corruption and its corrosive consequences. And worse.

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It's back! Line Of Duty has returned for a third series, and the good news is it's great TV... the bad news is, its portrayal of the police is so eeringly convincing, viewers were left feeling uneasy

'We both know the easiest way to get away with killing someone. Be a police officer.'

So said a detective to a sergeant – one that he (rightly) suspected of having done precisely that.

The first episode quickly spelled out that for Series Three, creator-writer Jed Mercurio had upped the ante.

This time round, the corrupt cops that are the show's hallmark and his forte, had guns.

Happily, he had retained the dry, grey, atmosphere that pollutes his depiction of modern-day policing and helped make its debut in 2012 so distinctive and popular that the fate of DCI Tony Gates (played by Lennie James) became BBC2's best-performing drama for a decade and the follow-up (with Keeley Hawes as the calculating DI Denton) equally acclaimed.

New blood: We saw Sergeant Danny Waldron (played with explosive energy by Daniel Mays) recognise Ronan Murphy - a man suspected of 'preparing to commit a gangland execution' – during a briefing before his Armed Response Unit was dispatched to arrest Murphy

Series Three arrived with perfect timing to prove British television was a match for any 'Nordic Noir' or cool quality crime series from HBO or Netflix.

Following War And Peace, Happy Valley, The A Word, and The Night Manager it also meant the BBC is on a roll with competition for the BAFTAs absurdly fierce already, even though it's only March.

The new storyline was as intelligent, unpredictable, and uncompromising as always, maintaining the show's trademark tension and intense interrogation scenes.

But it was immediately more high-octane and sensational – mostly because Mercurio had chosen to make the characters under suspicion Authorised Firearms Officers, looking at the procedures and pressures surrounding the type of Armed Response Unit that is becoming increasingly prevalent on our streets.

The opening immediately established the identity of the corrupt copper whose practices would be investigated by the team as the heart of the plot. Or so we thought…

 TV talent: This Is England star Vicky McClure is back as specialist Detective Constable Kate Fleming

We saw Sergeant Danny Waldron (played with explosive energy by Daniel Mays) recognise Ronan Murphy - a man suspected of 'preparing to commit a gangland execution' – during a briefing before his Armed Response Unit was dispatched to arrest Murphy.

When he cornered him, the bent cops in Line Of Duty's previous series might have led us to expect Danny was going to warn Murphy off or help him get away.

But even though Murphy dropped his gun, shockingly Waldron shot him – three times in the head.

When the rest of the team caught up, he brazenly re-arranged the crime scene (firing Murphy's weapon before planting it by his hand) and intimidating his colleagues into corroborating his story that he had killed him in 'self-defence'.

He had appalled and alienated them but kept them on board by threatening either them or their families.

Drama: New boy Sgt Danny Waldron gets himself into a typically gritty drama right off the bat

Evidence: Waldron hadn't banked on Forensics finding crucial evidence against him in regards his shooting of criminal Ronan Murphy

But Waldron hadn't banked on Forensics finding his hand had suspicious traces of gun residue from Murphy's pistol or that three separate members of the public contradicted his explanation, stating there had been significant pauses between the shots.

(These were referred to not as 'eye-witnesses' but 'ear-witnesses', which was a novel addition to the cop show lexicon.)

He had also under-estimated the dogged, dour, scepticism of anti-corruption unit AC12 officers Superintendent Ted Hastings (Adrian Dunbar), DS Steve Arnott (Martin Compton), and DS Matt 'Dot' Cottan (Craig Parkinson).

Three more miserable, humourless, questioning individuals you couldn't hope (or hate) to meet.

Riled by Waldron's exuberant bravado, they smelt a rat – mostly because he had covered his tracks too well, raising their suspicions about the fact the other officers had missed and their statements corroborated his version of events so thoroughly.

Dream team: Waldron had also under-estimated the dogged, dour, scepticism of anti-corruption unit AC12 officers Superintendent Ted Hastings (Adrian Dunbar, left) and DS Steve Arnott (Martin Compston, centre)

Investigating: DC Kate Fleming was sent in undercover to glean information on the killing

'Entirely consistent in every detail,' Hastings mused pointedly before accusing 'you shot him down like a dog.'

If Waldron had watched the previous two series he would also have been more suspicious about a new officer joining the team when they were being investigated by AC12 and that they invariably sent in DC Kate Fleming (played by Vicki McClure) undercover to glean information.

She wasn't exactly subtle either.

'Did it really happen the way you all said it did?' she asked the only one of Waldron's colleagues who hadn't followed his orders to fire over Murphy's dead body thereby incriminating them too.

'Don't ask,' Hari advised her. 'I don't think you've got any idea what he's capable of.'

He was right too.

Ronan Murphy was just the first name on Danny's list. He turned up at the house of Murphy's uncle Linus wearing CSI-style overalls and brandishing a gun he'd pocketed during a drugs raid.

He made him strip and tied him to a chair menacing: 'every time you don't do what I say, it gets worse.'

When the man still didn't recognise him Waldron explained the connection between them, albeit just a fractured, tortured, one.

On the front line: Ronan Murphy was just the first name on Danny's list. He turned up at the house of Murphy's uncle Linus wearing CSI-style overalls and brandishing a gun he'd pocketed during a drugs raid

'I never knew his name, not really. We did have a name for him though,' he spat about Murphy, hinting at avenging something he'd suffered in his childhood. 'For so many years I wondered what I'd do to him if I ever saw him again. And then I did.'

Rage blazed through him as he seethed: 'we had a name for you too', kicking over the chair, leaning over, and hissing into his face: 'with Ronan it was over too fast. But I've got you to make up for that.'

Linus Murphy thus became the third name to be crossed off his list.

It seemed a nifty twist to the perennial serial killer theme in shows like Luther – where the culprit was a Dirty Harry-style cop.

More reasons to watch: Also appearing in the third series of Line Of Duty, is Will Mellor as PC Rod Kennedy, and Leanne Best as PC Jackie Brickford

Waldron's reign of terror and his role as the increasingly violent villain didn't last long though.

Just when we were settling into enjoying Steve Arnott and the others' game of chess to entrap the Armed Response Officer, Mercurio brought all our assumptions to a crashing halt by giving Danny a taste of his own medicine.

A single shot rang out during a drugs raid and Kate Fleming ran upstairs to find Waldron on the floor with blood gushing from his neck and the colleagues he had threatened into supporting his story over the shooting of Ronan Murphy standing around him, watching him bleed out, doing nothing to stop him dying.

Mercurio was taking no chances.

If he didn't have viewers already hooked, he surely did now.

An early favourite for the BAFTA? Following War And Peace, Happy Valley, The A Word, and The Night Manager it also meant the BBC is on a roll with competition for the BAFTAs absurdly fierce already