Line of Duty 5 has aired its final jaw-dropping moment, rounding off a series that has featured some of the best scenes yet.
Creator Jed Mercurio is known for throwing viewers a curve ball with shocking twists that take the story in a completely different direction than expected.
We couldn’t even begin to guess at the final twist of the feature-length series finale, but it's definitely joined the hall of fame for the show's best surprises so far.
***WARNING: Spoilers ahead***
Tony Gates opts out
Back in series 1, we had no idea what twists and turns we’d be subjected to, although the brutal killing of Jackie Laverty (Gina McKee) by the balaclava gang was certainly a clue.
The very first subject of AC-12’s investigations was DCI Tony Gates (Lennie James), whose conviction rates seemed too good to be true.
Dodgy crime figures turned out to be the least of his problems when his lover Jackie was killed in front of him and he was blackmailed by the murderers.
As it emerged that gang boss Tommy Hunter had a mystery inside man in Gates’ department and the details of his affair with Jackie began to be exposed, he realised his career was over but insisted that he had not been corrupt.
In the final episode Gates asked DS Arnott (Martin Compston) to tell his wife he’d died in the line of duty – and then shockingly stepped in front of a truck on a motorway.
Straight afterwards, we realised that one of Gates’ officers, Matthew 'Dot' Cottan (Craig Parkinson), was Hunter’s inside man known as The Caddy.
Watch out for the window
When former Call the Midwife star Jessica Raine was cast in series 2 as DC Georgia Trotman, we briefly thought AC-12 had gained a new regular.
However, her time on the unit really was brief when she accompanied Arnott on a fateful visit to a hospital to try to question an injured witness.
The team were investigating a bungled police escort of the witness in which every officer apart from DI Lindsay Denton (Keeley Hawes) was killed, and had observed Denton trying to contact the witness.
But they were intercepted by a man disguised as a nurse, Arnott was knocked unconscious, and Trotman paid the ultimate price for having seen the killer’s face – she was thrown out of the window of the hospital ward, several stories up.
Danny Waldron – suicide or murder?
By series 3, we were well aware that Line of Duty has no problem in killing off its stars during early episodes.
Still, that didn’t make the death of Danny Waldron (Daniel Mays) any less gasp-worthy at the end of episode one.
Waldron was under investigation by AC-12 for a botched arrest where he shot and killed the suspect, and we later saw him spy on the funeral, follow home one of the mourners who he tortured and murdered, and leave a list of people who’d abused him as a child, including his two victims, in a letter addressed to Arnott.
DI (then DC) Fleming (Vicky McClure) was sent to work undercover with Waldron’s team, but when they went to raid a drugs house and he ordered her to stay downstairs while he and the rest of the team went upstairs, the plot began to thicken.
Fleming ran upstairs after hearing shots to find Waldron dying from a gunshot wound, which the rest of the team insisted was self-inflicted.
It later emerged that the rest of the team were trying to cover up a messy struggle that ended with Waldron being shot, but there were many more shocks to come in series 3…
Aside from the AC-12 trio, the best-known characters in the show are Dot 'The Caddy' Cottan, and DI Lindsay Denton – and the pair’s fates were intertwined.
We first met Denton when she was having her head flushed down the loo by her team, who blamed her for the deadly police escort raid which saw every other member of her operation killed.
There were so many twists and turns to Denton’s story: that she bottled her alcoholic, nuisance neighbour and got away with it; her questionable relationship with Arnott; having her hands scalded by prison officers while in custody; being kidnapped by corrupt officers while on day release; and eventually overturning her conviction for conspiracy to commit murder.
But the biggest surprise of all came when Cottan tracked her down and tried to bribe her to hand over some information that could convict members of the OCG.
Despite having been fired from the force in disgrace, Denton stayed true to her police roots and instead emailed the information to AC-12, knowing that Cottan was about to kill her.
Urgent exit required
As it turned out, Cottan didn’t survive too much longer than Denton, and he even bowed out over a similar attack of conscience.
The evidence was starting to mount against the bent copper, who by that time had been installed on the inside of AC-12, but he took things too far by trying to convince Hastings that Arnott was The Caddy.
Cottan fell apart under questioning, but just as the team were about to expose him, he texted “urgent exit required” to numbers filed as Removals, Talk and Ride, and within seconds armed officers supposedly guarding the department had fired shots into the interview room to bust Cottan out.
Fleming managed to shoot Cottan’s getaway driver, but just as a balaclava man went to shoot her, Cottan jumped into the line of fire, saving his old colleague.
In a final act of redemption, Cottan recorded a dying declaration that lead to a number of arrests, but was unfortunately tampered with before anyone could hear conclusive evidence about H’s identity.
As AC-12 closed in on her, Biggeloe sent the now-familiar text - although things didn't work out as planned when Fleming and Arnott realised what she'd done and brought in their own armed police to protect the department.
In fact, the OCG turned on Biggeloe, with a planted junior officer trying to stab her in the toilets in a bid to stop her talking.
Roz Huntley’s wake-up call
Series 4 began with the most heart-in-mouth episode yet, with a tussle between DCI Roz Huntley (Thandie Newton) and FC Tim Ifield (Jason Watkins) over conflicting evidence about whether a suspect could be guilty.
The pair got into a huge row at Ifield’s flat and Huntley stumbled backwards into a counter, apparently killed by an accidental blow to the head.
But just as viewers felt convinced the series had killed off its biggest name in episode one, things took an even weirder turn.
A panicked Ifield returned home from a hardware store with everything he knew he would need, as a forensics professional, to dismember the body and dispose of the evidence.
Just as he fired up the chainsaw above Huntley’s head, she woke up to possibly the most terrifying scenario imaginable.
Next thing we knew, Huntley was back at work like nothing had happened and Ifield’s body was discovered at his flat - with three fingers missing.
Unarmed and dangerous
The missing fingers had a great deal of significance to Huntley – it turned out that in the struggle to get away from Ifield, he had dug his nails into her arm.
Removing his fingers seemed the quickest way of removing her DNA from the scene, but unfortunately, Huntley’s refusal to get her arm wound seen by a doctor for fear of being linked to the crime caused huge problems.
Huntley became infected with MRSA, her injury deteriorating over the course of the series, until she eventually passed out and woke up in a hospital to find her arm had been amputated.
She blamed her distinctly shady husband for giving consent as a backlash against her telling him that she wanted to leave him, and he was later discovered to have links to the balaclava gang.
By now, keen Line of Duty viewers can spot a doomed character from a mile off, but the brutality with which characters are disposed of is still shocking every time.
The balaclava OCG’s favoured method of murder is throat-slitting, and there have been some particularly gruesome ones, beginning with the home invasion of Jackie Laverty.
Series 5 has featured two noteworthy cut-throat moments with the deaths of PC Maneet Bindra (Maya Sondhi) and undercover rogue officer John Corbett (Stephen Graham).
Bindra’s days were numbered from the moment she started being blackmailed by ACC Hilton to inform on AC-12, and when her department found out what she’d done it lead to her immediate sacking.
Poor Bindra had only just been showing videos of her new baby to Fleming, and in an effort to put things right, tried to double-cross the OCG, which was never going to end well.
Of course, she ended up with her throat slit but what made the murder even more shocking in hindsight was that it was ordered by Corbett, who was later identified as an undercover officer.
Corbett was determined to be a convincing enough gangster to find his way right to the top of the OCG and expose H, but unfortunately, he put his trust in Lisa McQueen by asking her to help him rat out the rest of the gang.
As it turned out, McQueen set him up to have his own throat slit, although not without some struggles with her conscience.
H is 'definately' Hastings
All fingers seem to have been pointing to Superintendent Ted Hastings (Adrian Dunbar) as top corrupt officer H, which we can’t quite believe as a) it’s too simple, and b) it would break our hearts if the gaffer was bent.
However, one twist from series five that made us gasp out loud was a seemingly tell-tale spelling mistake.
McQueen and Corbett had been communicating with H via messages on a laptop, where in one of H’s instructions he made the spelling error “definately”.
We later saw the cybercrime team carefully posing as H to try to get to the OCG by sending messages to the laptop, but Hastings acted completely out of character by recklessly jumping in and taking control of typing out some messages that went off script.
His message included the word “definately”, causing cries of outrage in living rooms up and down the land.
Whether it was a code word, a genuine mistake that showed him up or simply a reflection of the generally poor state of literacy that both he and H made the same error, remains to be seen as things still weren't clear by the series end.
Ever since Cottan's dying declaration in which he gave the codename H, the identity of the top crime boss has been an obsession with fans.
Many hoped they'd finally discover who H was at the end of series 5, but a further twist was yet to come...H is not one person, but four.
Arnott realised while watching back a video of the dying declaration that Cottan's fingers were actually tapping out the Morse Code for H at the same time - four dots, which AC-12 deduced meant four corrupt officers, or four Caddies.
That means there's still one Caddy at large, who we're willing to bet is more powerful and skilful than the others, and it's still anyone's guess who that person is.
Although Hastings is off the hook for now, there's still plenty of his weird behaviour that is unexplained, and his AC-3 nemesis DCS Patricia Carmichael (Anna Maxwell Martin) appears to be hiding murky motives, too.
Bring on series 6.
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