All eyes were on on AC-12 this Sunday as Superintendent Ted Hastings, Detective Inspector Kate Fleming and Detective Sergeant Steve Arnott finally closed in on the identity of 'H'.
But while we've all been totally gripped by the drama, some viewers have been left wondering whether it was based on true life events.
While Line of Duty was technically a fictional drama, many of the storylines feel as though they could be real.
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So, was the BBC series based on true stories or was it totally made up?
Is Line of Duty based on a true story?
Line of Duty creator Jed Mercurio works with a team of ex-police advisers when creating the show to ensure that the right procedures are being carried out and that it mirrors reality.
The plot lines and characters are fictitious and do not mirror real events, however, they are inspired by criminal cases that have happened in the UK.
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One of the biggest are the obvious parallels between the Lawrence Christopher plot from season six and the real life murder of 18-year-old Stephen Lawrence, one of the UK's most notoriously racially motivated crimes
There were numerous tips made to police about five suspects from a local gang, but it took officers two weeks before arrests were made.
The Crown Prosecution Service ruled there was 'insufficient evidence' to charge the five suspects. Stephen's family then launched a private prosecution, which saw three suspects being acquitted.
There was national outcry at the ruling, and in 1997, an inquest was launched into Stephen's death, which ruled he has died in an unprovoked and racially motivated attack.
Mercurio recently revealed that some plots within the drama are inspired by real-life cases, declaring: "Really relevant examples in British legal history include Stefan Kiszko.
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"And the other one is Barry George, who was convicted and then acquitted of the Jill Dando murder."
Both Kisko and George spent considerable amounts of time in prison before their convictions were overturned.
Does the AC-12 really exist?
Some fans have wondered whether the AC-12 - the specialist anti-corruption unit in the show - actually exists in real-life policing.
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While AC-12 doesn't exist under the same name, there are similar real-life anti-corruption branches of police across the UK.
The Metropolitan Police has a version known as the Directorate of Professional Standards.
Previously, the squad was nicknamed 'the ghost squad', because so little was known about it.
The unit had also originally been called the 'A-10', bearing striking similarities to the fictional AC-12
What do real police think of the drama?
It has been reported that a real-life police officer actually advises on Line of Duty storylines.
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The officer - named only as John - told The Telegraph in 2017: "Jed will always use dramatic licence, but there are very few places where he'll push the boundaries of what police work is really like.
"The job can be a lot more complex and time-consuming than we're sometimes able to show in the series, but I've spoken to officers of various forces and ranks, and they recognise the fundamentals of day-to-day policing are there."
Cressida Dick, Commissioner of the Met Police, however, is much less impressed with the show's portrayal of corruption in the force.
In 2019, she told the Radio Times: "I was absolutely outraged by the level of casual and extreme corruption that was being portrayed as the way the police is in 2018-19 - it's so far from that."
Featured Image Credit:Topics: TV & Film, Line of Duty