Line of Duty season 6 episode 3 leaves us with some big questions and theories – could Jo Davidson be "H"?

Anyway. There was a lot of detail to absorb from the episode, and a lot of theories to explore. Take a look at our run-down of the episode:

1. Is DCI Jo Davidson "H"?

In the closing seconds of episode three, Davidson opened up her laptop and logged in to a very, very familiar messaging service. Yes, it's definately the same interface we've seen used by the OCG to communicate with "H"!

"All under control now," wrote Davidson (though her face betrayed a different story). And all we saw in response were three little dots, indicating that the "unknown user" was typing a response. Roll credits.

So. We know Davidson is caught up somehow in the OCG (as confirmed by the burner phone drop-off at the end of episode two). This scene also confirms that Davidson has tried to solve her problems and throw AC-12 off the scent by sacrificing DSU Ian Buckells (Nigel Boyle).

But it also raises questions about where Davidson sits within the network of corrupt cops.

To recap: Hastings is still in search of "H", the "fourth man" (or woman) who serves as a crime boss within the police force. AC-12 has now decided that's what DI Dot Cottan (Craig Parkinson) really meant when he responded to the letter "H" in his dying declaration, and then used his hand to tap out the morse code for H (dot, dot, dot, dot). The "four dots" were Dot Cottan himself, plus Gill Biggeloe, Derek Hilton... and one more. But who is it?

At this point, it could well be Jo Davidson. Perhaps she is "H", and perhaps she was communicating with someone in the OCG to keep them informed about what's going on inside her team. Or, perhaps Davidson is relatively junior in this network, and the person at the other end of the conversation is "H" (a more senior police officer she has to report back to). Or maybe neither of the people in this conversation is "H". Or maybe "H" doesn't exist. Maybe YOU are "H". Hhhhhelp.

2. What are Jo Davidson's motives?

Whether Jo Davidson is "H" or not, we do know that she is mixed up with organised crime. But... why? What's her deal?

Because, frankly, it doesn't seem like Davidson is getting any pleasure out of this. You don't have a screaming-hitting-the-car-windows-crying-fit if you're doing this for fun, and you're just an evil schemer who enjoys a life of crime. Framing her ex-partner Sergeant Farida Jatri (Anneika Rose) as a rat was, to Jo, a necessary but extremely painful move. She doesn't seem to have many qualms about Buckells, but the death of innocent cop Lisa Patel (Tara Divina) stops her in her tracks.

In previous seasons of Line of Duty, we've seen diligent cops get drawn in to corruption and the OCG network through a series of poor choices (like DCI Tony Gates, played by Lennie James, whose slip-up was to arrange a cover-up for his mistress when she claimed she'd run over a dog while driving drunk.)

So what is Jo Davidson's backstory? Is she being blackmailed? Is this something to do with the family she claims not to have; perhaps with her next-of-kin, Samantha Davidson? When did she start working with the OCG – before or after she came onto the Gail Vella case? Is she getting money? Was she enjoying herself until she got in too deep?

3. Is Buckells bent?

Since the beginning of season six, we've been wondering whether Buckells is bent or just incompetent. But now Davidson is pointing the finger at her own boss Buckells, claiming that she brought DI Kate Fleming (Vicky McClure) onto her team because she specifically wanted a police anti-corruption expert to check things out ("I knew you'd come through for me").

But is Buckells bent? Let's take a deep dive.

So, the first thing to discuss is the issue of the Directed Surveillance Authority. As you might recall, the police established in-situ surveillance of Beechwood House as soon as the call from the CHIS handler came in, identifying "Ross Turner" as Gail Vella's killer.

Davidson asked Buckells: "You OK to sign off the Directed Surveillance Authority?"

But the next morning, during the time when Davidson diverted her convoy to the armed robbery at the bookie's, the surveillance team had to pull out for several hours because (as Kate summarised to Davidson) "it got queried as requiring Intrusive Authority because they were using extreme high-powered lenses to view inside the property... looks like the Super [i.e. Buckells] messed up the paperwork."

The OCG (almost certainly) used this sizeable surveillance gap to grab Carl Banks from his flat, swap him with Terry, clean up both flats, cover them with newspaper clippings of Gail Vella, plant evidence, and take Terry's freezer to the dump. Then they killed Carl Banks, dumped his body, and tried to stage it as a murder-suicide with the CHIS (Alistair Oldroid).

None of this could have happened if the paperwork hadn't been "messed up", or if that mess-up hadn't been queried (by who?) or if it had actually been flagged to someone who could quickly fix it, or at least alert the team heading to the arrest. But was it really Buckells's mess-up? After all, Davidson only asked him to sign off on "Directed Surveillance Authority" – and perhaps as her boss he should have noticed she actually needed Intrusive Surveillance Authority, but he doesn't seem to have questioned her request.

Presumably for strategic reasons, in her AC-12 interview Davidson refused to name Buckells as the person who'd messed up the paperwork. But at the exact right moment, she shared this information with Kate (who reacted as if this was *brand new information*, and as if she hadn't been the one who originally told Davidson that the Super had messed up the paperwork. Weird! Continuity error or Kate playing along?)

Hopefully we'll soon get a fuller explanation. But as Buckells goes into his first AC-12 interview, here's the other 'evidence' against him:

• According to Davidson, he was the one who recruited Ryan Pilkington, which was unusual because he replaced a higher-ranking officer when she transferred off the team. "Not me," she says to Kate. "That was Buckells' idea. Family friend or something. Probably got a nudge down at the Masonic Lodge."
• Buckells has framed golfing pictures in his office, and actual golf clubs. The subtext: is he linked to Tommy Hunter (the OCG leader in season one, who was arrested on a golf course) as well as Dot, AKA "The Caddy"? Is the whole thing based on a network of golf-loving cops and criminals?
• Some crucial Operation Lighthouse files on the Gail Vella case – specifically, the files in which it's suggested that Vella's recordings and notes could have been taken from her house in a burglary – went missing before all the documents were turned over to AC-12. Anyone on the team could have "disappeared" them in the gap between AC-12's first (abortive) raid on the MIT and their second, but now they have turned up in Buckells' car.
• Deborah, who claims to have witnessed a row between the CHIS Alistair Oldroid and Terry Boyle (Tommy Jessop) in the pub, seems to have been set up by someone to give false testimony. As Kate suggests to Davidson, the setter-upper could be Buckells: some years ago, Deborah was arrested for assault, and it was Buckells who was instrumental in getting charges against her dropped, so maybe she owed him a favour.

4. Is Buckells being framed?

Almost certainly! That "all under control now" message confirmed what we already suspected during the episode: Davidson is setting her boss up to take the fall. It's hard to see any other way to interpret events.

And some of the evidence against him is pretty weak, circumstantial, or possibly planted. Let's take a look:

• To start with, Davidson was the one who asked for "Directed Surveillance Authority", and Buckells just went along with it without questioning. Perhaps he should have realised that "Intrusive Surveillance Authority" would be needed for the operation – but incompetence / trust in Davidson could go a long way to explaining this important admin mistake.
• The connection between Buckells and Deborah could just be a coincidence; perhaps Buckells was just being his usual lazy self at the time, and he couldn't be bothered to deal with an assault case. And after all this time, would that be enough leverage to persuade Deborah to give a false statement to police, pinning the blame on Terry? Surely it's possible that someone else has got to Deborah?
• While the missing files in his car are suspicious, they would also be very easy to plant, if someone (cough, Davidson) were trying to frame him.
• Ryan's recruitment is harder to account for, so it'll be very interesting to see what his explanation is on that point. But if a pal of his at the gold course did indeed persuade him to take on Ryan, that doesn't necessarily mean that Buckells knows his pal's true motives.

If Buckells is being framed (as he surely is), the next question is whether the attempt to pin this all on him will be successful.

5. Does Kate still suspect Jo Davidson – and what will she do about Ryan?

Figuring out what's really going through Kate's mind has been quite difficult this season. At the end of the episode, she seems to have bought into the idea of DSU Buckells as the guilty party – arresting him and marching him off to AC-12. You don't do that to your team's big boss unless you're serious about it.

But Kate is smart and diligent. Surely she will spot the ways in which things don't add up? Particularly, Kate is well aware that everything points to the OCG killing Gail Vella and being involved in frustrating this case every step of the way – and yet the SIO (Davidson) doesn't want to see it.

Perhaps she is still playing the long game with Davidson, getting closer into her confidence to find out the truth?

A big insight into the above question will surely come in the next episode – when Kate either does, or doesn't, tell Davidson that new recruit PC Ryan Pilkington (Gregory Piper) is a former juvenile offender who worked with the OCG and once tried to chop Steve's fingers off with a bolt cutter.

And will she tell Davidson about her (incredibly well-founded) suspicions that Ryan tried to murder key witness/suspect Terry Boyle, and succeeded in drowning the officer driving the police car?

Now that she and Steve have finally worked out where they've seen Ryan before, it remains to be seen what they do with that information, and who they trust to share it with. But Ryan cannot be allowed to just keep going around killing his fellow officers without consequences.

7. Will Jo and Farida's relationship be discovered?

Jo Davidson's tactic thus far has been to pretend that Farida is a fantasist who imagined their whole relationship. That makes Farida's claim that Jo planted the burner phones in her house sound pretty bizarre. But will she be able to maintain this charade?

In Davidson's favour, there is the fact that she never let Farida meet her family and friends. She never let her into her life, and they never fully lived together. Conveniently, Jo recently removed the last of her belongings from Farida's house.

But AC-12 have their suspicions, which is why they have ordered another forensic search of Farida's house. Will they find evidence of Jo Davidson all over the place? She certainly seems worried about it, when she calls DS Lomax to find out why there are forensic tents at Farida's place again ("I just happened to be driving past...").

And can you really hide all evidence of a relationship like that? Are there really no photos, no mementos, no WhatsApp messages?

8. What will Steve do after discovering Steph's money?

Steve has an unfortunate/useful habit of sleeping with people he's investigating. In this case, it was literally just sleeping – quite sweetly spooning with Steph Corbett (Amy De Bhrún) after she apologised to him for leading him on, and opening up to her about his own sexual difficulties after his back injuries.

But once she was out of the house, Steve put his detective hat back on and followed up on his suspicions about Steph's financial affairs and why she was back in contact with Hastings. In the attic he found an envelope of cash.

Does Steve know what's really going on? Will he make the connection that Hastings gave her £50k of the £100k he hid after playing along with the OCG and taking a "bribe"? (The other £50k was found and confiscated by police.) If so, what will he do about it? Would he betray Hastings? Will he guess why Hastings felt compelled to give over the money?

9. Is Steve going to be busted for drug addiction?

Hastings and Steph gave Steve a wake-up call about his painkiller addiction, which has spiralled out of control as his back injury has troubled him more and more. After talking to Steph, Hastings arranged for all of AC-12 to go through "routine drug testing", but strategically delayed Steve's test – hopefully for long enough that the drugs were out of the system, though he did turn to drinking as a way of getting through the pain and the detox.

It seems unlikely that it's as simple as that, though. Steve is still in deep trouble with his reliance on painkillers, and with his debilitating injury which he is hiding from doctors so he doesn't get taken off his job or put on desk duty. "My job's pretty much the only thing I've got left," he told Steph.

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10. Are Wise and Sindwhani corrupt?

PCC Rohan Sindwhani (Ace Bhatti) and DCC Andrea Wise (Elizabeth Rider) are a very irritating double act, who are perpetually getting in AC-12's way. Both of them are keen to deny any institutional corruption in the police force. They are wary of negative press, and always have one eye on PR.

That could be the entire explanation behind their antagonism towards AC-12, and DCC Wise's obstruction of AC-12's first raid on the Hill, and their complaints any time Hastings arrests another police officer.

Or... one or both of them could be bent! Either of them could even be "H"! PCC Sindwhani himself clearly had beef with journalist Gail Vella, walking out of an (unaired) interview with her when she pushed him on police corruption and alleged collusion in sex abuse.

11. Will Terry talk to AC-12?

Getting Terry Boyle in for an interview is top priority for AC-12. They now suspect he was "cuckooed" – a practice in which criminals take over a vulnerable person's home to use it as a base, often for drug trafficking.

Terry's freezer has been recovered from the tip, with traces of Jackie Laverty's blood in it – so now they know (as viewers already knew) that she was stored in there between 2012 and 2019. They can make the link to the OCG and start to tie things together. "This is it. The whole damn thing," as Hastings put it.

But interviewing Terry is easier said than done. Firstly, he could still be in danger from Ryan's murderous intentions: though his safe house (aka "approved premises") has been put under AC-12 surveillance, Ryan is a crafty lad who (because he's in the MIT) knows exactly where Terry is being kept, and has the ability to intimidate him.

Secondly, Terry is under strict instructions not to tell the police anything. Thirdly, Terry has Down's Syndrome and has learning difficulties, so he can find it hard to recall details and to respond to questions.

And fourthly, DCI Jo Davidson will surely try to block AC-12 from getting the approvals they need to interview Terry away from her own team's prying eyes; after all, she stopped the previous police interview with him just when he started speaking, because she was (possibly rightly) worried about his wellbeing and level of distress.

12. Is Kate going to die?

Look, this episode just gave us a bad feeling about Kate's future. Ryan knows that she's onto him, and he has zero qualms about murdering anybody who gets in his way (police officers apparently being his specialty). And if Kate now chooses to trust Davidson and tell her about Ryan, that could put her in a dangerous position. Alternatively, if she goes after Davidson, that could be another route to a sticky end.

Her rapprochement with AC-12 (a curry invite from Steve; a friendly nod from Hastings) actually got us worried. Just when the team's making friends again, could showrunner Jed Mercurio be planning a major character death?

Line of Duty continues on Sundays at 9pm on BBC One. Take a look at the rest of our Drama coverage, or check out our TV guide to see what's on TV this week.