Line of Duty – the famously twist-ridden tale of police corruption and intrigue peppered with initialisms and crime fighting jargon – given fans a twist with e pisode five of series six, another heart-pounding cop drama.
The instalment saw the return of one of AC-12’s most wanted in the form of Tommy Hunter.
But just who is Tommy Hunter? Has he been in the show before, and what does he reappearance mean for the future of the series?
Here is everything you need to know.
Spoilers for Line of Duty series 6 episode 5 follow
What happened in episode five?
At the end of episode four, a partial DNA match was found on the police database, a mystery blood relative of AC-12 adversary, acting DSU Joanne Davidson (Kelly Macdonald).
As part of this week’s latest instalment, it was revealed that Davidson was in fact a match for organised crime mastermind John Thomas “Tommy” Hunter, who plagued the unit during Line of Duty’s earlier series.
The DNA match was so close, it was said the samples amounted to "homozygosity" (the degree to which both copies of a gene have the same genetic sequence), which hints heavily at Hunter being Davidson’s paternal parent.
Who is Tommy Hunter?
Hunter – played by Scottish actor Brian McArdie – first appeared in Line of Duty way back in series one.
At first, he was simply an ominous voice heard through a burner phone, but one who was involved with all sorts of illicit activities – sex trafficking, drug dealing and armed robbery to name just a few.
By implicating that series’ protagonist DCI Tony Gates (Lennie James) in the murder of Gates’ lover Jackie Laverty (Gina McKee), Hunter was able to manipulate him into doing his bidding.
Gates went rogue, and eventually captured Hunter, who confessed to his crimes, but not before it was revealed a member of Gates’ team was working for the crime boss the whole time.
Hunter’s inside man advised him to give the police intelligence and plead immunity to enter the witness protection programme. That’s where Hunter began series two, as ‘Alex Campbell’, a protected witness living in a safe house.
Former criminal associates remained nervous that Hunter would rat them out to the police, and so a hit on him was ordered as a means of taking him out for good.
Since a series two all-action shootout, Hunter has been thought dead by AC-12, though his name has cropped up between then and now, with his links to the roots of foiled operations stretching far and wide.
Is Hunter really Davidson’s father?
Many viewers had speculated that Hunter may be Davidson’s father, given both carry Glaswegian accents.
Those who rubbished the idea pointed to the 14-year age difference between the pair, but given Hunter’s grim history with sexual abuse, we may yet find out more uncomfortable truths about him.
But even so, the twist still came as something of a shock, thanks in part to the show’s labyrinthine writing.
We’ve already seen Davidson lament her lack of family, even wading into heated arguments with former girlfriends over her roots, of which she has remained frustratingly tight lipped.
If she’s related to Hunter, that unwillingness to discuss her past is not unwarranted, and her relationship to the crime lord could actually explain her involvement with Central Police.
Ever the criminal mastermind, it’s possible Hunter indoctrinated her and steered her towards a career in the force as an asset that would serve his interests for years to come.
This being Line of Duty, we’re currently swimming against a tide of questions until we get to the answers, some of which may never even come.
But one thing’s for sure, the final two weeks of the crime thriller are sure to be more gripping than ever.