Line of Duty series 4

The fourth series of the British police procedural television programme Line of Duty was broadcast on BBC One between 26 March and 30 April 2017. It is the first series to air on the network after the first three were broadcast on BBC Two.

The series follows the fictional Anti-Corruption Unit 12. AC-12 is lead by Superintendent Ted Hastings (Adrian Dunbar) and by his team DS Steve Arnott (Martin Compston), DS Kate Fleming (Vicky McClure). They are also assisted by PC Maneet Bindra (Maya Sondhi) and DC Jamie Desford (Royce Pierreson), who is briefly assigned to the team. The unit investigates DCI Roz Huntley (Thandie Newton); she is suspected of arresting the wrong suspect after ignoring forensic evidence presented by Forensic Coordinator Tim Ifield (Jason Watkins). Over the course of the investigation she implicates her husband Nick (Lee Ingleby) and his lawyer Jimmy Lakewell (Patrick Baladi). Supporting characters include ACC Derek Hilton (Paul Higgins) and DS Sam Railston (Aiysha Hart).

The series was commissioned along with the third after the success of the second. Line of Duty was created by Jed Mercurio who executive produces the series alongside Simon Heath and Stephen Wright. Cait Collins produced it. Filming took place in late 2016 with Mercurio directing two episodes and John Strickland directing four. Anna Valdez Hanks and Stephen Murphy provided cinematography. The series was nominated 21 awards of which six were won. It also received significantly higher viewing figures than previous series and mostly positive reviews from critics leading to the commissioning of series six. The fifth series returned to BBC One in 2019.

Main

 * Thandie Newton as DCI Roseanne "Roz" Huntley
 * Martin Compston as DS Steve Arnott
 * Vicky McClure as DS Kate Fleming
 * Adrian Dunbar as Superintendent Ted Hastings
 * Jason Watkins as FC Tim Ifield

Starring

 * Paul Higgins as ACC Derek Hilton
 * Aiysha Hart as DS Sam Railston
 * Maya Sondhi as PC Maneet Bindra
 * Lee Ingleby as Nick Huntley
 * Patrick Baladi as Jimmy Lakewell

Recurring

 * Gaite Jansen as Hana Reznikova
 * Claudia Jessie as DC Jodie Taylor
 * Patrick FitzSymons as DCI Mark Moffatt
 * Mark Stobbart as DS Neil Twyler
 * Scott Reid as Michael Farmer
 * Anneika Rose as PC Farida Jatri
 * Elva Trill as Gemma Riley
 * Royce Pierreson as DC Jamie Desford
 * Vineeta Rishi as FC Rupal Pandit
 * Nigel Boyle as DCI Ian Buckells

Guest

 * Harriet Cains as Jade Hopkirk
 * Craig Parkinson as DI Matthew "Dot" Cottan
 * Tony Pitts as DCS Lester Hargreaves

Production
On 8 April 2014, the BBC confirmed that Line of Duty would return for a third and fourth series. Following the success of the third series, a fifth was commissioned at which time it was reported that future editions of the programme would move from BBC Two to BBC One. Although BBC One originally passed on the series when creator Jed Mercurio pitched it to the network, the decision to move the show came after high viewing figures and a restructuring of the networks. Mercurio wrote the series, and executive produced it alongside Simon Heath for World Productions and Stephen Wright for Northern Ireland Screen, which was produced by Cait Collins.

Actors Martin Compston, Vicky McClure, and Adrian Dunbar returned to the series. Thandie Newton joined the series as Detective Chief Inspector Roz Huntley, the latest police officer to be investigated by AC-12. Additionally, Jason Watkins was cast to portray Forensic Coordinator Tim Ifield. Aiysha Hart, Maya Sondhi, Lee Ingleby, Patrick Baladi, Royce Pierreson, and Tony Pitts also appear. Despite being killed off in the previous series, Craig Parkinson filmed new footage of his characters dying declaration.

Mercurio directed the first two episodes of the series while John Strickland returned to direct the final four episodes. Anna Valdez Hanks served as the cinematographer for episodes 1–3 and Stephen Murphy took over for the remaining three episodes. Filming on the series occurred in Belfast from 29 August to 16 December 2016. It consisted of six hour-long episodes. Five days after broadcast transmission concluded, Line of Duty was commissioned for a sixth series.

Broadcast and streaming
The series was first broadcast in the United Kingdom on BBC One from 26 March 2017 and concluded six weeks later on 30 April. In the United States, it was added to Hulu on 1 May 2017. It can also be streamed there on Acorn TV and BritBox. In Canada and Australia the series streams on Netflix.

Critical response
On the review aggregator website Rotten Tomatoes the series holds an approval rating of 100% based on 15 reviews. Den of Geek's Louisa Mellor commended the amount of action in the series opening episode stating that there was a "car accident, an abduction, an escape attempt, a police chase, a firebomb explosion and a rescue" all before the opening credits. Sam Wollaston, writing for The Guardian, considered the action to be over-the-top and suggested there were plot holes writing that "Perhaps that's what happens when writer and director are the same person. There is no one around to say: hang on a minute, are you sure?" Rachel Cooke of The New Statesman wrote that the second episode was "as well built as any in the last series" but feared that Line of Duty would become a "pastiche of itself" as Mercurio attempted to top himself.

Once the series concluded, Sarah Hughes, also with The Guardian said she enjoyed the fulfilling end to the series but noted the how it addressed real-world problems saying "Tim Ifield and Huntley were victims of their own knowledge in that, as experienced police officers, both believed a plea of self-defence wouldn't save them and chose instead to try and cover up their crimes." Newton's character was however, praised by critics who noted the complexity of Huntley's actions and the motivations behind them. The Irish Independent writer John Boland opined that the series "came to a nail-bitingly exciting end, or rather to three nail-bitingly exciting ends, two of them unforeseeable by even the most imaginative of viewers." The Guardian ranked the series number two on their "50 best TV shows of 2017" list. Digital Spy however, considered the fourth series to be the worst out of the programmes six.