Line of Duty series 5 recap: 6 major questions after a dramatic penultimate episode

• Who is ‘H’ in Line of Duty? Meet the suspects
• Meet the cast of Line of Duty
• Line of Duty: who exactly was Jackie Laverty?

And mother of god, there were plenty of developments elsewhere. Not only did DS Steve Arnott’s (Martin Compston) physical problems stall his relationship with murder cop Sam Railston (Aiysha Hart), but key figures from the OCG were brought down in an armed police raid. While Lisa McQueen (Rochenda Sandall) is now in custody, henchman Miroslav (Tomi May) is no more after taking several bullets to the chest.

However, all that action has left us with a lot of questions. From Hastings' history, to Lisa’s allegiances and Corbett’s corpse, here are the biggest mysteries to emerge from episode five.

1. Is Ted Hastings being framed? And if so, by who?

The climax of the episode saw Ted Hastings cornered in a tense police interview, for once answering to corruption claims rather than fielding them.

After discovering Hastings’ visit to jailed OCG member Lee Banks at Blackthorn Prison (more on that below), DI Kate Fleming (Vicky McClure) and DS Steve Arnott finally decide to report their gaffer to anti-corruption, kickstarting an AC-3 investigation into Ted.

Led by careerist Detective Chief Superintendent Patricia Carmichael, the unit searches Hastings’ shabby hotel room, finding an envelope containing £50,000 in cash, a tidy sum handed to Ted by shady ex-detective Mark Moffat ­– the man who claimed to be representing property company Kettle Bell Complex.

However, in the interview, Carmichael and fellow investigators DI Brandyce (Laura Elphinstone) and PS Tranter (Natalie Gavin) reveal that the money is clean of Moffatt’s fingerprints. And despite Hastings’ claims the cash was “an advance of funds that were due to me further down the line”, AC-3 revealed that Kettle Bell hasn’t made a recent withdrawal of £50,000.

Was the money, as we've suspected before, a ploy to recruit Hastings to the OCG?

It soon gets much worse for Ted. With help from some damning financial records fraudulently obtained by Lindsay Denton (Keeley Hawes) in series two, AC-3 determines Hastings failed to declare his spiralling debt.

And from this Carmichael concludes he has the motive (money) and the means and opportunity to have played a part in Corbett's death. But that's not all; following his arrest, Carmichael goes on to state she's determined to take the investigation against Ted even further. “Today is just for starters. I’m going to prove Hastings is ‘H’,” she tells a shocked Kate and Steve.

Is Carmichael correct or is Hastings being framed, as he claims?

While there have been plenty of loaded clues throughout the series to indicate that Ted is a bent copper, it’s certainly possible he’s being set up. Sure, it wasn’t wise to keep hold of the cash for so long, but do the notes really prove Hastings is corrupt?

After all, the fact the AC-12 boss was sent cash in the first place is a big indication he isn’t ‘H’: why would the OCG try to recruit a man who was already bent? And if Ted is a criminal kingpin then why would he be broke and living out of a crummy hotel?

But if Ted isn’t corrupt, then who is trying to frame him? The obvious answer is the real ‘H’, of which there are plenty of suspects. However, the £50,000 package could have been sent by anyone with the money to spare ­– and a connection to Mark Moffatt.

Could a further investigation into Moffatt and the source of the envelope provide more evidence here? Or will Hastings himself be able to shine some light on the situation?

2. Did Ted actually tip off Lee Banks?

During his interview with AC-3, Hastings finally opens up about his very suspicious trip to OCG member Lee Banks in Blackthorn prison. However, his account isn't too convincing. When Carmichael asks him to give a reason for the visit, the AC-12 leader does little to dispel the idea he passed on information that blew Corbett’s cover.

Despite claiming Banks is a “hardened criminal”, Hastings says he approached the gang member in a bid to uncover intel about the “personnel of the OCG and other details that might be useful to our inquiry”.

“I am the superintendent of the team that got him banged up and put behind bars,” Hastings tries to explain. “If he helps me with my inquiry, I’ll put a word into the court so they can take into account his co-operation when it comes to sentencing.”

This simply doesn't add up. Those connected with the balaclava gang are in no doubt what will happen to them if they grass – remember lawyer Jimmy Lakewell? "There are some people there's no immunity from," he told Steve at the end of series four, before declining the offer of a witness protection scheme.

Surely as a “hardened criminal” Banks would never entertain Ted's offer? He knows there's no escape if he turns police informant so it's a little unbelievable that the AC-12 boss could get him talking so easily.

Plus, if Hastings visited Banks as part of AC-12’s investigation then why did he fail to mention it to his team? What did Ted have to hide?

On the other hand, if Hastings is actually ‘H’ and wanted to tip off the OCG about Corbett then why use Banks anyway? Couldn’t he have reached out to members of the gang who aren't behind bars?

It’s also worth bearing in mind that Kate, Steve and AC-3 only know about Hastings’ visit thanks to information from Lisa, a key member of the OCG. Although reluctant to hand over any other information in her interview with AC-12, she doesn't hesitate to say she was informed about Corbett’s real identity from Blackthorn prison. A tad suspicious, no?

Is it possible that she found out about Corbett’s real identity through other means but was ordered by the real ‘H’ to tell investigators about Blackthorn? Is Lisa a pawn in the conspiracy to take down Ted?

It's also worth returning to Lakewell – he's likely still resident of Blackthorn, serving a prison sentence for perverting the course of justice. Could he have maintained his connections to 'H' and the OCG and leaked Corbett's real identity to Lisa on orders from above? (Also, notice how this shot neatly mirrors Ted in his police cell at the end of the most recent episode.)

3. Why did the OCG dump Jackie Laverty’s body with John Corbett’s?

Jackie Laverty, series one’s crooked property developer (not connected to Kettle Bell, as far as we know...), was back in episode five for another gruesome cameo.

Murdered in 2012 in order to blackmail DCI Tony Gates ­– with whom she was having an affair – Laverty's corpse had been thrown in a freezer owned by Terry, a man with Down’s Syndrome who's regularly exploited by the OCG, and forgotten about.

Although we got a glimpse of her icy remains in episode four, her body has now finally fallen into police hands, discovered in a bag alongside the remains of John Corbett.

Why were the two bodies dumped together? The simplest explanation is that the OCG wanted to kill two birds with one stone. This supposes that since they had already planned the disposal of Corbett’s remains, the OCG figured it efficient to finally get rid of Laverty’s body, too. Even killers can't ignore good economics.

But there are a few things that don't quite add up. Why not just leave her corpse in Terry’s freezer? If the OCG had been happy to abandon Laverty there for the past seven years then why not keep her hidden? Or use her body to blackmail another copper, as they have done so many times before?

It seems more likely they had a specific reason for wrapping up Laverty and Corbett in a location that would be easily discovered by police.

Was it to send a signal? It's possible Lisa and co want to make crystal clear that the two bodies were dumped by the OCG, with police knowing from Gates that Laverty was murdered by the gang years before.

But why bring this up now? Is it part of a conspiracy to frame Hastings as ‘H’, perhaps? Would dumping Laverty’s body be an effective way of linking the AC-12 boss to another OCG murder other than Corbett's? Will Laverty, a property developer, be somehow linked to Hastings and Kettle Bell?

4. Did John Corbett's mother Anne-Marie pass on information to Ted Hastings during his time in the Royal Ulster Constabulary?

At the start of episode five, more evidence is uncovered about a link between John Corbett’s Irish family and Ted Hastings.

Kate and Steve discover that Corbett’s mother, Anne-Marie McGillis, went missing in April 1989. Based in Belfast, she was suspected to have passed on information to the Royal Ulster Constabulary before she was kidnapped by paramilitary forces.

Her remains were discovered 12 years later in 2001. Forensics learned that before she had been killed by a bullet to the head, Anne-Marie had been shot in her wrists, knees and ankles.

The wounds are very significant: not only are they signs of paramilitary torture, but they mirror the injuries suffered by Roisin Hastings, Ted’s estranged wife, at the hands of John Corbett.

To link Hastings and Anne-Marie further, we also learn that soon after her disappearance in 1989, Ted was promoted to Sergeant before an extended leave of absence under medical advice.

As Steve comments, Hastings has previously opened up about a serious injury from his RUC days: in the show's first series he recalled how a pipe bomb explosion sent him into intensive care and killed his "best mate". Was this the reason Hastings was on leave in 1989? And could Anne-Marie have passed over information to a young Ted Hastings in 1989?

Did paramilitary forces discover this and take revenge on Hastings – and Anne-Marie? Is that why Corbett was gunning for Hastings for so long?

While we’re not exactly sure at this point, we do know who might enlighten us: Corbett’s wife Steph (Amy De Bhrun). It’s likely she knows the full story, asking John over the phone in episode four, “Do [the police] know about Anne-Marie?”

Although she's so far pretended to hate her husband, will Steph finally crack after learning about John's death and reveal his full motives to the police?

5. What is Lisa McQueen really up to?

Will the real Lisa McQueen please stand up. At the moment, her behaviour is quite the puzzle: although in episode four we saw the OCG henchwoman in a private moment of despair after Corbett’s killing, Lisa didn’t show a single sign of weakness in episode five.

In fact, we saw little emotion during her interview with AC-12. Considering it's her big opportunity to finally escape the criminal gang by co-operating with the police, she plays it very cool. Too cool, perhaps.

Lisa must know that witness protection and immunity won't keep her safe: we all know it's no defence against the balaclava gang (just look what happened to Tommy Hunter).

Her claim that she found out about Corbett’s real identity from a prisoner at Blackthorn is taken at face value by Carmichael and her team. But is it true? Was she told to leak this information by ‘H’? Is that why Lisa is concerned with who is watching footage of her interview?

If nothing else, at this point we can strike off the theory that Lisa is another undercover cop. Unless she’s gone full method, she surely would have revealed herself as an officer when taken into police custody.

6. Has Lisa disproved the theory that Hastings ordered Corbett's killing?

One of the key questions we had after episode four was whether Ted Hastings had ordered the murder of John Corbett. Speaking to members of the OCG through a police laptop, the AC-12 boss seemed to drop a cryptic command to Lisa, writing, “I need you to bring all this to a close.” Soon after, Corbett was slain – and it was suggested that Lisa had acted on a command, rather than orchestrating the murder of her own volition.

However, events in episode five indicate Hastings didn’t order the hit.

Think back to the AC-12 boss's impromptu 'undercover' operation starting in the OCG’s nightclub. Although Lisa and Miroslav seem unsure whether he is the top corrupt copper when he enters, they seemingly decide he is ‘H’. After all, they take Hastings to the warehouse where the £50m haul from the Eastfield police depot robbery is stored. Why bring him to such an incriminating, high value location if they aren't convinced he's 'H'?

Yet Hastings – as 'H' – repeatedly asks to speak to "Clayton" AKA Corbett. If his message in episode four had been some sort of veiled order, Lisa would never have believed him to be 'H' and taken him to the warehouse, a move which ultimately led to her arrest and Miroslav's death.

Of course, you might argue that Lisa secretly knew Hastings wasn’t ‘H’ and was planning to kill him all along. Yet if that was true, she wouldn't have taken him to their warehouse just to shoot him.

The logical conclusion: Lisa assumes ‘H’ doesn't know about Corbett's death because she wasn't acting on his/her orders. And Ted did not order the murder in the scene we were shown in episode four.

It’s an interesting development that further complicates Lisa’s role: if she took the decision to kill Corbett alone, acting purely on the Blackthorn tip-off, then why was she so upset by his death?

Was it just the pain of Corbett’s betrayal? Or was Lisa hoping to avoid any killing, much in the same way she spared Sergeant Jane Cafferty’s life in the series opening?

Yet if Lisa was truly feeling remorse and becoming increasingly unhappy with life in the OCG then why she didn’t she take the chance to break free of them? She had a good opportunity when speaking to AC-12.

Did she think ‘H’ was watching the interview and was too scared to come clean? Or, more intriguingly, are we watching Lisa struggle to reconcile two sides of herself?

Whatever’s Lisa’s story is, it's probably not over yet.

Line of Duty continues on Sundays at 9pm on BBC1