Four stars

WE viewers are so sophisticated these days. With our degrees in The Sopranos and masters in Game of Thrones, you won’t find us shouting excitedly at the screen like punters from the black and white ages at their first Elsie Tanner v Ena Sharples rodeo.

Unless, that is, we are watching Line of Duty, the fourth series of which ended last night as it began, on exhilarating, nerve-shredding, bellow-at-the-telly form. This wasn’t just any old Sunday night drama, this was defibrillator TV.

Audiences have come to expect certain things from show creator Jed Mercurio besides a willingness to kill the audience’s darlings. Prime among them is a doozy of a finale in which revelations land like Anthony Joshua upper cuts. The list of questions that required answers last night was as long as a week in Barlinnie.

Who would turn out to be balaclava man? Ditto the mysterious “H” named as the top dog in the network of corrupt officers the show has been trying to expose since it started in 2012. Is DCI Roz Huntley (Thandie Newton) really as bent as a nine bob note? And would Greenock’s Martin Compston, adopting a flawless Mockney [CORRECT] accent throughout as DS Steve Arnott, finally crack and yell “Aw gie’s peace!” when the answers were finally in? An estimated seven million-plus viewers, a rarity in the multi-channel age, switched on to find out.

The cast duly assembled for the last hurrah like a bloodied army returned to the battlefield. Roz was missing a hand, Arnott was absent [CORRECT] the use of his legs, while Superintendent Ted Hastings (Adrian Dunbar) had lost a large chunk of his dignity having been served with notice that he was himself under suspicion.

Roz has spent the past five weeks annoying the bejeezus out of Ted. “The wee witch”, as he called her last night, has been the meteor heading towards his dinosaur ways, calling him out on everything from his sexist language to his funny handshake. If she was going down in flames for framing a suspect, was Ted about to suffer the same fate for being “H”?

It looked like the rightful order of things was being restored once Roz entered AC-12’s glass box of doom. On the other side of the table was Hastings, DS Kate Fleming and Arnott, swiping away at his iPad like a good ‘un in textbook Line of Duty style. This was it, the moment of truth. But a glance at the watch showed there was still a good 20 minutes to go. Mercurio wasn’t finished yet. Oh no.

What happened next? For the benefit of the DIR (which, as all fans of the jargon-peppered show is the Digital Interview Recorder), the TV reviewer is shaking her head and performing a “zipped mouth” mime indicating no comment. Those who watched last night will know, and if you are waiting to see it on catch up tonight, enjoy – and good luck dodging spoilers.

Enough to say that Mercurio delivered on a wham bam ending. Admittedly it wasn’t as much of a knockout as the finale to series three, complete as that was with car chase, a shootout, and the declaration of a dying man, but it was enough to send the heart racing. By the end of it all the story had been brought to a point where it can go in potent new directions in the fifth season, date of arrival yet to be determined. There is a lot of this line left to walk, particularly, as Mercurio has hinted, where Ted is concerned. For now, take a breath folks. Recover. See you back on duty soon.