07/04/2019 10:37 BST | Updated 19/03/2021 15:59 GMT

Line Of Duty Season 1 Recap: Here's What Happened During AC-12's First Investigation

Lennie James and Gina McKee featured as DCI Tony Gates and Jackie Laverty in the first series of the BBC drama.

Back in 2012, Line Of Duty started out as a small show tucked away on BBC Two before it eventually blew up and moved to the main channel and became one of the UK’s biggest dramas. 

And while its popularity has grown, there has been one thing that has remained a constant over the course of the last five series – its twists and turns. 

Ahead of the sixth series launching, we’ve recapped the whole of the first to bring you up to speed with the case of DCI Tony Gates...

DCI Tony Gates (second left) was the subject of AC-12's first investigation

AC-12′s first case saw them investigate DCI Tony Gates, after his high success rate on his cases spiked their suspicions, with DS Kate Flemming placed undercover in Gates’ team.

However, the case was much more complex than the “laddering” (a process in which a number of different charges are placed on the same defendant to increase an officer’s number of successful cases) they suspected him of. 

Gates was having an affair with a woman called Jackie Laverty, and after she claimed to have hit a dog while drink-driving, he agreed to cover it up for her by staging a break-in at her home and making it look like her car was stolen. However, he was horrified to later discover Laverty hadn’t actually hit a dog, but had killed a man during the “accident”.

In reality, she had killed her accountant after he discovered she had been laundering money for gangster Tommy Hunter, and had threatened to tell the police. 

Gates is having an affair with Jackie Laverty, who is laundering money for gangster Tommy Hunter

At the instruction of Hunter, Laverty was later murdered after masked raiders stormed her house during a passionate encounter with Gates. Hunter then framed an unconscious Gates by putting his fingerprints on the murder weapon, used this fabricated evidence to blackmail Gates into helping him. 

After a tip-off from an undercover Flemming, AC-12 arrived at Laverty’s house, only to find Gates at the house claiming he’d come to arrest her, and had discovered her dead. 

DS Steve Arnott grew increasingly determined to nail Gates, convinced he was involved in Laverty’s money laundering, and soon discovered she had used some of the money to pay his kids’ school fees. 

With Arnott hot on his tail, Gates was backed into a corner and agreed to help AC-12 track Hunter down. 

After finally catching up with him, Hunter admitted to Laverty’s murder and the killing of three drug dealers, claiming to be operating under the instruction of an inside man. A conversation between Hunter and one of Gates’ officers, DS Matthew ‘Dot’ Cottan, revealed that he was the inside man, known as ‘The Caddy’. He and Tommy went back a long way, as Cottan had carried Hunter’s golf bags as a kid, hence his codename. 

However, Cottan’s true identity remained a secret to his police colleagues, and he continues to operate from the inside. 

DS Matthew Cottan was revealed as a corrupt police officer known as The Caddy

Realising his career was over, the series ended with Gates taking his own life, instructing AC-12 to tell his family he was killed “in the line of duty”, thus earning the series its name. 

Tommy Hunter was then placed under witness protection, setting the series up for its next chapter...