12 questions and theories we have after that dramatic second episode of Line of Duty season 6

1. So is Jo Davidson fully bent - and working with the OCG?

At this point, it's looking likely that DCI Joanne Davidson (Kelly Macdonald) is straight-up bent.

On the night that the call came in from the CHIS handler with information about "Ross Turner", someone – probably Jo – made a call from a burner phone to the OCG, warning them that her team was about to storm the property.

Later, when she realised she would need to frame another member of her team, she let herself into Farida's house (using the house keys we saw her decide to keep in episode one) and planted a bag of burner phones, including the one used to make the call about the raid.

At the end of the episode, we saw her leave prison, collect her car, and go straight to a nighttime rendezvous at an underpass, where a dodgy-looking bloke in a van completed the hand-off of a new burner phone.

She then had a melodramatic crying fit in her car, hitting the windows and sobbing – possibly indicating that she's unhappy to be working with the OCG, or unhappy to have had to frame Farida.

Can there be any innocent explanation for her behaviour at this point? Surely not. The burner phone drop-off is damning.

But if Joanne Davidson is bent, and is working with the OCG, then that raises more questions. Who put her on the Gail Vella case, a month after the victim's murder; is there someone more senior than her who is also working for the OCG, and made that decision? Or did she manage to engineer it herself? And if AC-12 hadn't come along, what would her end goal be – just to make sure the case went unsolved until it was closed?

2. Is Farida being framed?

It seems evident that Jo Davidson is trying to frame her ex-girlfriend, PC Farida Jatri (Anneika Rose), as the rat who passed on information to the OCG.

Presumably, Jo planted the phones in Farida's house before heading to her AC-12 interview, given she has a set of keys – and, after all, she was the one who suggested to AC-12 that they raid the homes of Farida, Lomax, and Buckells (having pointed out that any one of them could have leaked information about the police raid, just as easily as she could).

This could, of course, all be an elaborate double bluff. Perhaps Farida was the one who made the call. But if she was, why would she sneak off to AC-12 and bring attention to Operation Lighthouse in the first place? Puzzling.

Also, here's another thing that's puzzling me: Jo must have known that Farida would tell AC-12 about their long-term relationship and ugly break-up during the police interview. So why not get ahead of the game and tell them herself?

Anyway. At the moment, Farida is in custody and Jo is roaming free, so the (presumed) attempt to frame Farida is going very well. It remains to be seen whether more evidence against Farida will appear, or whether AC-12 will buy this version of events.

3. What happened during the raid on Beechwood House?

I have to admit – I am struggling to get my head around exactly how everything played out during the raid on Beechwood House. Please get in touch if you've got it all figured out. Please, I'm begging you!

So: let's say Jo is bent, and she made the call to the OCG giving them the heads-up that her team was coming for "Ross Turner" (Carl Banks) that evening. Presumably that's when they roped in a handful of amateur criminals and arranged an armed robbery on a bookie's, so Jo could divert her convoy – buying the OCG extra time to break into Banks's flat, kill him (or kidnap him and kill him elsewhere), and replace him with Terry Boyle (all while carrying out a thorough clean of the property before the police got there).

But! Detective Superintendent Ian Buckells (Nigel Boyle) then denied Jo Davidson's request for an immediate raid – delaying the whole operation until the morning. Did this catch her by surprise? Or were they colluding?

Jo and her team then set off in the morning, instead. But what I don't understand is, given the delay, why the armed robbery on the bookies still took place.

As Superintendent Ted Hastings (Adrian Dunbar) pointed out, it's weird that anyone would rob a bookie's in the morning, when takings are at their lowest and it's broad daylight. So, surely, this must be because the original plan was for the robbery to happen the night before. But perhaps more importantly, why did it still need to take place when the criminals had ample time to clear out overnight?

Perhaps this is connected to the issue with the directed surveillance authority. It was only during the diversion (in the morning) that Buckells's admin mix-up came to light: as Kate put it, “When we were diverted to the armed robbery there was some confusion over the surveillance authority…. the team was only in place under directed authority, and it got queried as requiring intrusive authority because they were using extreme high-powered lenses to view inside the property. Which means they had to pull out until it was sorted. Looks like the Super [i.e. Buckells] messed up the paperwork.”

When she says that it "got queried", who did the querying? Why only at that point? Why go through the whole charade with the armed robbery in the morning, when the surveillance gap was all that was needed for Carl Banks to be removed from the property, anyway? Also: why did Jo Davidson protect Buckells and refuse to name him in her AC-12 interview?

Surely this must all make sense. My brain is tired.

4. Did Kate really betray AC-12?

At the moment, it looks like DI Kate Fleming (Vicky McClure) betrayed the confidence of DS Steve Arnott (Martin Compston) purely to protect her own career and her new position on as Deputy SIO on the Murder Investigation Team. Screw AC-12!

Faced with the options of either a) becoming an AC-12 informant or b) being accused of being an informant anyway, she came up with an option c) and gave Jo Davidson a heads-up about AC-12's investigation and forthcoming raid. As Superintendent Hastings puts it, Kate has picked her side.

But though Steve is apparently broken-hearted at his old pal's betrayal, I just cannot believe this is all that's going on. Despite fan theories that Kate is "H", she has always been a diligent cop devoted to bringing down bent coppers. And as an experienced undercover officer, Kate is also excellent at playing a part and hiding her true motives until the right moment.

Could Kate be playing the long game? Perhaps she passed on the information about AC-12 as part of a strategy to get closer to Jo Davidson, and gain her confidence. Perhaps she is acting on her own, and will bring valuable information to AC-12 when the timing is right.

That could also explain why she and Jo are now going out for drinks together, and making eyes at each other, and Kate is asking her if she wants to hang out at the weekend. (Alternatively, perhaps there is real chemistry there and their friendship is genuine.)

Or perhaps Kate is already undercover for a different anti-corruption team, like AC-3? Or perhaps she is working for AC-12 again, and Hastings and Steve's visible anger at her betrayal is just an elaborate double (triple? quadruple?) bluff?

This can't just be a straightforward betrayal. I'm sure of it.

5. Is it just a coincidence that Ryan has joined the team?

Jed Mercurio has been playing the long game with Ryan Pilkington. The character, who is played by Gregory Piper, first appeared in season one as a troubled and troublesome young offender working for crime boss Tommy Hunter. He then returned in season five as a fully-fledged member of the OCG. And then, at the end of that season, we discovered that he was taking his career in a new direction – having decided to train as a police officer.

So, Ryan is the OCG's man on the inside in season six. But how did he end up on DCI Joanne Davidson's team after PC Farida Jatri transferred out? Does Jo know he's bent? Is that why he's been selected for the role, or is it just a coincidence?

Also, Ryan is in grave danger of being recognised, but somehow he has got away with it so far. His 'friend' Terry Boyle has already been released on bail, so nobody seems to know about that connection, and they won't have to come face-to-face; Ryan also managed to hide his face when Steve turned up to raid Operation Lighthouse. (Last time he met Steve, he tried to lop off his fingers with a pair of bolt cutters.)

Kate definitely recognises him from somewhere (and keeps giving him sly looks), but she still hasn't placed him. And Ryan is still pretending not to know why she knows him.

But is it a matter of time? And how will Ryan's presence on the team play out?

6. What did Gail Vella know?

As expected, the likely motive for journalist Gail Vella's murder is emerging... and it probably comes down to a story she was working on about police corruption and organised crime. What do you know!

In their search for a motive, the AC-12 team (now including Shalom Brune-Franklin as DC Chloe Bishop) first decided to re-watch some old news clips from their previous investigations, featuring Gail Vella as the reporter for MN News.

First up there was the inquest into the police shooting of Karim Ali; that was the anti-terror operation that Steve refused to help cover up in season one, which resulted in his transfer to AC-12. Then there was the time that retired Chief Superintendent Patrick Fairbank was found guilty of sex abuse charges.

In each of these cases, Gail Vella was on the scene. She pointed out to viewers that witnesses disputed police accounts, and she reported allegations that Fairbank suppressed investigations into a wider network.

"Sir, Gail Vella drew attention to links between organised crime, politicians and senior police officers," Steve said. "And these are just the reports we found in our own archive."

Hastings wasn't entirely convinced this was enough to get her killed, pointing out: "there's no evidence to suggest that she dug up anything that wasn't there before." But then, finally, something clicked for Steve: "Maybe she was working on something that would." Aha!

A trip to Gail's old newsroom helped to back up this theory. Her one-time producer Nadaraja (Prasanna Puwanarajah) showed Chloe and Steve an unaired clip in which Gail gave some strident commentary after PCC Rohan Sindwhani (Ace Bhatti) announced that police corruption inquiry Operation Pear Tree was officially closed.

"Some will wonder why this news is being announced over a holiday weekend," Gail said, in a piece-to-camera that was destined never to be broadcast. "Cynics might conclude that the police and crime commissioner isn't examined too closely. Perhaps Mr Sindwhani has learned the secret to high office appears no longer to reside in revealing the deepest truth, but in telling the most attractive lies."

Nadaraja then gave AC-12 some even more intriguing info. Gail had been inspired by a podcast about police corruption surrounding the murder of a private detective called Daniel Morgan, and so she was gathering material to make a podcast of her own. She was pursuing several senior police officers for interview, but was murdered before she could release the podcast.

We also learned that Gail's notes and files have gone missing. Nadaraja said he told the original detectives he suspected a burglary, but they seem to have dismissed this because there were no signs of forced entry at her home – and her computer and laptop were apparently still there. (Question: did Nadaraja talk with the Operation Lighthouse detectives before or after DCI Jo Davidson took over as SIO, a month after the murder?)

But as AC-12's cyber expert Amanda Yao (Rosa Escoda) quickly deduced, the laptop at Gail's place wasn't actually hers. Someone had just put it there to make it seem like it was hers. "The digital forensics team have triaged the desktop computer and the laptop computer. Truth is they're remarkably clean," she said. Very few personal files were found, and applications were on factory settings. Later, swabs of the keyboard and screen found no trace Gail had touched them.

But there was a partially-downloaded audio file on the computer, from an interview with (presumably) a police officer, who tells Gail: "There are some people you can't challenge."

As an explanation for why this audio file has made it onto the switched-out computer, Amanda suggested: "When the murderer installed the replacement devices, they would have synced to her phone momentarily, and started to import the audio file before the murderer broke the link."

They'd need her passwords, though, and it remains to be seen whether this theory makes sense. I'd also be interested to know if her phone has been swapped out, too – or if anything was backed up onto the cloud.

All of this sleuthing by AC-12 has quickly brought to light new evidence and a possible motive. So why didn't Operation Lighthouse work this out in a year of fruitless investigation?

7. Who actually killed Carl Banks and the CHIS?

Despite a concerted effort to make it look like the CHIS (covert human intelligence source) Alistair Oldroid killed Carl Banks and then himself, this seems highly unlikely. It just doesn't make sense. Why would he do that?

It's more likely, as Hastings says, that both were murdered consecutively and it was staged to look like a murder-suicide. But the whole thing is too transparent.

It's far more likely that Carl was killed as retribution for blathering down the pub about killing Gail Vella (and also to prevent any future confessions to police or anyone else). And then the CHIS was pushed off a building so he couldn't talk, either.

This looks like the work of the OCG.

8. What is the relationship between Steph Corbett and Hastings?

So, Hastings is still in touch with Steph Corbett (Amy De Bhrún)! You'll remember her as the widow of John Corbett (Stephen Graham), the undercover officer who was killed by the OCG in season five. Thanks to the manipulations and machinations of Gill Biggeloe (Polly Walker), John wrongly believed that Hastings was responsible for the death of his mother, Anne Marie McGillis.

As viewers know, Hastings made a terrible misjudgement in season five when he secretly visited a prison to pass on information to an OCG member (Lee Banks), blowing John Corbett's cover. According to writer Mercurio, he believed this would bring John back in as he'd have to quit the undercover op, but it had the opposite effect – leading to John's murder by the OCG.

That explains Hastings' sense of obligation to Steph, and why he secretly gave her £50k of the £100k he'd 'pretended' to take as a bribe from the OCG in season five. (Presumably she doesn't know about Hastings' role in her husband's death.)

The £50k present also explains why Steph is back in touch with Hastings 18 months later, turning up in the lobby of his workplace to tell him: "You promised you'd call me back. It's HMRC."

If the tax office is suspicious that Steph suddenly has £50k in cash, that could be a problem.

9. Will Steve work out the truth?

HMRC is suspicious, and so is Steve. Curious about why Hastings shooed him out of his office to take a phone call – and then met up with Steph in the lobby – he dropped in to visit her at home, claiming to be on a job in the area. He then immediately started saying things like "that's a nice big expensive telly you have" and "gosh, it's great you were able to keep paying the mortgage" and "so you can afford Sky Sports huh?" (I'm paraphrasing here).

Steve evidently thinks Steph is richer than she should be, and he doesn't seem to buy that this is all from a life insurance payout. But does he suspect the truth? And if he finds out, would he dob Hastings in?

Complicating matters, Steph seems keen to get to know Steve a little better. Maybe even romantically. He accepted her invitation to come round again if he was in the area... but is he interested? Or is his injury still holding him back?

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10. Is Steve still planning to leave now he's been made DI?

Considering just how long Steve has been stuck as a Detective Sergeant, and the fact that he had to watch Kate blast past him (from DC to DS to DI), you might think he'd have been thriller to finally get a promotion to Detective Inspector.

But he didn't exactly look thrilled when Hastings pronounced: "I have been giving the situation some thought, and loyalty works both ways. I'm going to have to confirm it with HR, but ahead of the formal promotion process, I am making you a temp DI. Congratulations, son. You've earned it."

Why wasn't he thrilled? Oh, because he's thinking of leaving AC-12 – and how he's facing a conundrum. The feelers he put out with ex girlfriend/colleague DI Nicola "Jolly" Rogerson (Christina Chong) have paid off, and her Gaffer wants to talk to him about transferring. But now his own Gaffer has rewarded him for "loyalty", and so perhaps he's feeling guilty about wanting to go. Plus, the promotion is not official yet, and presumably it will only be finalised if he stays put at AC-12.

Then there's the fact that AC-12 finally has an interesting case to investigate (good), but it involves dealing with Kate, who has apparently betrayed their friendship (bad). Will he want to stick around to see this one through?

Personally, I think Steve will opt to stay in AC-12. But it's also possible that Hastings will find out that Steve has been looking elsewhere, causing dramatic friction between the AC-12 boss and his right-hand man.

11. Where is Steve's painkiller storyline going?

Steve's back pain seems to be getting worse and worse, as is his reliance on painkillers. In this episode, we saw him suffer through a particularly bad spasm which left him wincing, sweaty, and almost paralysed – to the point where he was desperately scrabbling to pop the blister packs that Steph Corbett had fetched him from his car.

Steve doesn't want anyone to know how much pain he is in, and how many painkillers he is taking. But Steph now knows. Will this be significant?

And as Craig Parkinson (who played DI Matthew "Dot" Cottan) pointed out in the official Line of Duty BBC podcast, the whole storyline must be going somewhere.

He mused: “I’m thinking that he’s slowly upped his drug take and now they’ve taken over him; I think this is going to be a major plot point during this season. Knowing what I know and also now being an avid audience member, Jed [Mercurio] does not put anything there for no reason, everything is to be explained and it means something."

12. Who is Samantha Davidson?

In a blink-and-you'll-miss-it moment (much like the sight of a silver getaway van down a narrow side street), we get a look at DCI Joanne Davidson's profile on the police database in this episode. Intriguingly, her next of kin is listed as "Samantha Davidson".

Considering what she told Farida (that she has no family), and considering her glass-chucking incident with the framed picture in her flat, we have to wonder who this is. Her mother? A sister...?

Other details which are worth noting down now, just in case: she was born on 22nd April 1979, and joined the police when she was 20. She trained at Melton Police College, and her training officer was C Stenhurst. And no, we've not met a Stenhurst in any previous seasons – I checked. You're welcome!

Line of Duty continues on Sundays at 9pm on BBC One. Take a look at the rest of our Drama coverage, or check out what else is on with our TV guide.