Adrian Dunbar, Vicky McClure & Martin Compston on Line of Duty's return
The fifth series of BBC hit crime drama Line Of Duty starts on Sunday evening, with a brand new case for AC-12 to tackle. Set nearly two years after the previous instalment of the Belfast-filmed series, Georgia Humphreys finds out more from cast members including Co Fermanagh star Adrian Dunbar.
NAIL-biting interrogation scenes, captivating guest leads and twists you will not see coming: that's right, Line of Duty is back for a new series on Sunday night.
Since it first became a hit back in 2012, writer Jed Mercurio has continued to up the ante with each series of the BBC crime drama about a police squad tasked with tackling corruption within the force.
This time, Stephen Graham and Rochenda Sandall join the cast as two pivotal members of an organised crime group, who, following a series of dramatic events, become persons of interest to AC-12.
Here, we get the lowdown from series regulars Vicky McClure, Adrian Dunbar and Martin Compston, as well as newbie Sandall.
:: THE SEARCH FOR 'H'
Co Fermanagh-born Dunbar (60) reminds us that series four ended with some mysterious shots of his character, Supt Ted Hastings, and that the possibility of Hastings being 'H' – the notorious leader of a network of corrupt coppers working for an organised crime gang – is "definitely explored".
"His background is explored in the series and it runs alongside the organised crime story," teases Dunbar, who has been with the show since its inception.
"So, we will be looking at Hastings - he will be under suspicion."
But, asked how he would feel if it turned out his character wasn't a good guy after all, Dunbar teases: "It would be very strange at this point for Ted to turn out to be a baddie, don't you think?"
Meanwhile, his Scottish co-star Compston (35) reasons: "With every cop we have investigated, they have had a weakness that the gang has exploited and used to their advantage, whether it be somebody cheating or financial gain, so it is a question of whenever that could happen to any of us."
:: LIVING UP TO EXPECTATIONS
Line of Duty has had impressive ratings – the final episode of series four drew in 7.5 million viewers – and real-life police are amongst the fans tuning in.
"I was in Swains Lane [in London] the other day and these cops came flying down the hill with blues and twos and they stopped and rolled the window down and went, 'Wahey!'" quips Dunbar, who's also known for his film work including The Crying Game and Hear My Song.
"But we get a lot of warmth from the public, they come up and say hello to us."
Does that mean there's pressure with series five to live up to people's expectations?
"There is, but it is a good pressure," suggests Compston, who was a professional footballer before becoming an actor.
"As long as we don't f*** up these scripts we are on to a winner – it delivers every year. That is probably my biggest nerves, when we haven't got the scripts yet, because that is the thing we can't control.
"I don't want to sound like one of the a***holes in a band going, 'this is my greatest album ever', but I think this could be our strongest year."
:: SECRETS TO THE SUCCESS
Anyone who's been a Line Of Duty fan from the start will know how important it is to pay attention to the different threads weaved throughout.
"It is a complicated show and we don't spoon-feed the audience," notes Nottingham-born McClure (35), who plays DS Kate Fleming.
Another of the original cast members, the This Is England actress reckons part of the appeal for viewers is trying to guess what might happen next.
"At the minute there is a lot of quite hard-hitting docs which are a bit shocking, but you go in [to work] and say, 'Did you watch it?' because you want to discuss it, and it is a similar thing with Line of Duty," she elaborates.
"People have got their own theories; some are way too far out there, but some are right on the nose."
Compston adds they're lucky the show started out on BBC Two, before progressing to BBC One, as it meant they built up a loyal fan base.
"I think we still stuck to the basics, and with Jed, nothing gets unbelievable; the situations might be unbelievable but how we react to them is how a police officer would react."
:: NEW FACES ON SET
McClure calls Graham – who was busy filming when the press day came around – "one of her best mates".
She admits she hasn't got an awful lot of scenes with him in Line of Duty but follows with a grin: "Knowing he was coming on this, I just went, 'Oh God, we are all going to have to pull our socks up again!'
"He is a powerhouse, he is something else and you see that from the minute he steps on screen."
Someone who did work with Graham a lot on this show is Sandall, who describes him as "electric" to work with.
"He really makes everybody else almost act better, in a weird way, because it is so real and truthful and passionate," she adds.
The actress was on her way to Ikea when she got the call to say she had the job.
"I totally lost it in the car and whizzed round Ikea and bought loads of unnecessary candles and batteries and a stuffed elephant for my nephew, and then I went and had some Swedish meatballs!" she recalls excitedly.
"It was fantastic."
:: WHAT TO EXPECT NEXT
A significant plot development from the last series was the discovery that officer Maneet Bindra, played by Maya Sondhi, had leaked some of AC-12's files.
Which is something we can expect to see explored further in the coming episodes, confides Dunbar.
"That is a very strong storyline that needs to play out," he says. "We do pick that up and run with that, so there will be a resolution to that."
We also previously saw DS Arnott left fighting for his life, after being badly beaten with a baseball bat.
And there are suggestions he may be struggling to fully recover from the attack.
"He is back on his feet definitely, put it that way," says Compston. "But with J's writing, nothing is ever as it seems."
Now, that's something we can well believe...
:: Line Of Duty returns to BBC One on Sunday March 31 at 9pm.