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Who is Line of Duty's Steve Arnott?

TV tonight Line of Duty
(Image credit: BBC/World Productions/Steffan Hill)

Everything you need to know about AC-12 action man Steve Arnott!

Well known for his signature waistcoats, Steve Arnott is one of AC-12’s best officers.

When he’s not being shot at, kidnapped by thugs or thrown down flights of stairs, he’s in the thick of an investigation. Right from the get-go, he’s been an anti-corruption legend, and Line of Duty season 6 suggests that isn’t going to change. Will he lead the charge against the OCG and discover who is H?

Here’s everything you need to know about Steve Arnott! 

What rank is Steve?

As of season 6, Steve has been promoted to Detective Inspector.

Who plays DI Steve Arnott?

Steve Arnott is portrayed by Martin Compston. Compston might have become a household name for his role at AC-12, but he’s also been in Traces, Mary Queen of Scots, Monarch of the Glen, Sweet Sixteen and The Nest, among many others!

What has Steve Arnott gotten up to so far? Spoilers ahead!

Season 1

In season 1, Steve Arnott transfers to AC-12 after refusing to participate in a police cover-up on a botched counter-terrorism operation.

Personally recruited by Ted Hastings (Adrian Dunbar), Steve is put to work on DCI Tony Gates’ case, whilst Kate Fleming (Vicky McClure) goes undercover at TO-20. He begins to work out that Tony is covering up Jackie Laverty’s hit-and-run and attempts to interrogate Jackie over her less-than-legal business. After a brief crisis of conscience over his role in AC-12, he commits to his new role in anti-corruption.

Steve is later captured and tortured by the OCG when he goes looking for Tony. Thankfully, Tony returns to rescue Steve from the thugs. With Steve convinced that Tony isn’t to blame for the murder of Jackie Laverty, he worked closely with the rogue officer to locate OCG leader Tommy Hunter.

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Season 2

Steve was an integral part in AC-12’s investigation of Lindsay Denton (Keeley Hawes). Steve got straight to work on the attempted assassination of Tommy Hunter, failing to intercept Tommy's killer at the hospital. This also saw his newest flame, DC Georgia Trotman, killed after she was thrown out a hospital window. 

After Kate’s cover at the Missing Persons Unit is blown, Steve began to build a rapport with Lindsay Denton himself. He visited Lindsay in prison to win her trust, telling her that he believes she’s innocent. Over the season, Steve built up a very close relationship with her.

As the case concludes, Steve finds the £50,000 bribe that she received from Lindsay Akers to help hand Tommy Hunter over to the OCG. This leads AC-12 to arrest not only DCC Mike Dryden, corrupt officer DS Manish Prasad and Lindsay herself for conspiracy to commit Tommy Hunter’s murder, and for perverting the course of justice.

Season 3

In Line of Duty’s third season, Steve came under fire from Lindsay as she fought her convictions. She alleged that he'd acted improperly whilst undercover. Those allegations drove a wedge between Steve and the other members of AC-12. 

Steve later took over the Linus Murphy investigation from Dot Cottan, aka “The Caddy” (Craig Parkinson). Losing confidence in AC-12 as he is more alienated from his fellow officers, Steve is forced to work closely with Lindsay. She had been released on parole, and he starts collaborating with her to investigate leads on Danny Waldron. 

Meanwhile, Dot begins to work against Steve, destroying evidence and ultimately building up a profile that suggests Steve must be The Caddy. In the final episode, Steve successfully picks enough holes in Dot’s fake story to exonerate himself, winning back AC-12’s trust.

Line of Duty Steve Arnott

Steve is always impeccably well-dressed.

Season 4

Steve is approached by forensic investigator Timothy Ifield. Tim is convinced the forensics suggest DCI Roz Huntley’s chief suspect is being framed. When Ifield goes missing, Steve pursues Huntley as Tim Ifield’s killer.

Later in the season, Steve is assigned a younger partner, DC Jamie Besford, to continue the investigation into Balaclava Man. When Steve visited Nick Huntley, he was beaten with a bat and thrown down the stairs by a gang member. 

After returning to work in a wheelchair and closing the investigation on Roz Huntley, Steve confronts Jamie, who is revealed as a mole for the OCG inside AC-12. Steve manages to retrieve Jamie’s gun and stops him from killing anyone.

Season 5

Steve’s main role in season 5 was as AC-12’s go-between with undercover operative John Corbett.

Corbett leaks info about the OCG’s sex trafficking operations and the raid at Eastfield, a high-security police depot. With Arnott drawn away by a false Status Zero call at the raid on Eastfield, Corbett goes to the ground, convinced that Steve isn’t as committed to exposing H as John himself is.

Steve and Kate work together to support Ted despite his growing recklessness in the operation. After DCS Patricia Carmichael accuses Ted of being H, Steve and Kate discover that Gill Biggeloe was involved in John Corbett’s selection for Operation Pear Tree. They successfully exposed Gill as the third member of H. Steve saves Gill’s life after shooting Tina Tranter, and she is placed into witness protection.

Martin Compston (Steve Arnott) and Stephen Graham (John Corbett) in Line of Duty

Martin Compston and Stephen Graham in the last series of Line of Duty

Season 6

Season 6 sees Steve at a low point in his life. Now that Kate has moved on to MIT, he has been given a new partner in DC Chloe Bishop, but he hardly seems happy. 

Ted’s having to be much more cautious than he has been up till now, and Steve is clearly upset by the lack of action. The only time he cracked a smile in the first episode was immediately after he swaggered out of Ted’s office.  As we've now seen, Steve has quite a large stockpile of drugs in his flat. If Craig Parkinson and Sarah Millican are correct on Obsessed With… Line of Duty, there’s a solid chance that Steve's addiction may well be a big problem as season 6 continues.

Line of Duty season 6 continues Sundays at 9pm on BBC One. Seasons 1-5 of Line of Duty are available to watch right now on BBC iPlayer. For even more shows to enjoy, check out our TV Guide.