What happened to Steve Arnott’s back in Line of Duty?

The AC-12 detective's injury has its roots in a key scene from series four

Line of Duty S5 - Episode 5

Although previously the Casanova of Line of Duty, DS Steve Arnott has kept womanizing to an absolute minimum in series five. In fact, we’ve been worried since the opening where Steve was spotted swiping through dating apps late at night before popping a painkiller.


However, Steve’s love life looks set to re-open in the drama’s penultimate episode. As an out-of-focus waistcoat in a preview photo suggests, the AC-12 detective will enjoy a drink with murder cop and former flame Sam Railston (Aiysha Hart).

Line of Duty S5 - Episode 5

We’re not expecting the evening to go well, though. As we can see from another preview sneak peek, at one point we’ll Steve gives himself a rather pained expression in the mirror (see main image).

Are the two pictures connected? And, more importantly, what injury is causing Steve so much grief?

Considering previous events in the show, it’s likely the source of Steve’s expression is the same reason he’s on painkillers: the attack he suffered at the hands of ‘Balaclava man’ – a disguised member of the OCG – in series four.

That chapter of Line of Duty revolved around an investigation into bent copper DCI Roz Huntley (Thandie Newton) and the murder of forensics officer Tim Ifield (Jason Watkins). Steve was on his way to question Huntley’s husband Nick Huntley (Lee Ingleby) about his wife’s whereabouts on the night of the killing when he was attacked.

Making his way to Nick’s office, the lift doors opened to reveal a balaclava-clad assailant who immediately jumped the detective. First smashing his face with a baseball bat, the OCG member then threw the AC-12 officer down a flight of stairs, leaving him for dead.

Steve Arnott after the 'Balaclava Man' attack in series four
Steve Arnott after the ‘Balaclava Man’ attack in series four

Later in the series, it emerged that Nick Huntley – whose wife tried to frame him for Ifield’s murder – had called criminal lawyer Jimmy Lakewell (Patrick Baladi) when he saw Steve approaching his office. On hearing the news, Lakewell contacted corrupt Chief Superintendent Hilton (Paul Higgins), who promptly ordered a mystery OCG member to attack Steve.

As you probably guessed, the AC-12 detective survived the attack, but we shouldn’t be too surprised if the injuries come back to haunt him.

“At the start of the series, by all intents and purposes, he looks like he’s made a full recovery, but as we go through the episodes you start to realise it’s not quite right,” Martin Compston previously teased before series five.

“There’s stuff wrong with him physically and that’s starting to affect him mentally and this will bleed into the current series.”

Martin Compston as Steve Arnott in Line of Duty, BBC iPlayer

Compston added: “I’m not sure how much we can give away, but in this series there is a certain problem that Steve has physically, which was a bit of an eye-opener when Jed told me about it.

“When you get down to the seriousness of it and how it affects him and his mental health, it turns out to be a very emotional scene.”


Line of Duty is on Sunday at 9pm on BBC1