Five years after a record-breaking 17 million viewers tuned into the Line of Duty finale, the BBC police drama remains one of British television's most talked-about phenomena. The much-anticipated conclusion to series six promised to unmask the mysterious 'H' - the fourth man colluding with organised crime - but instead left fans divided and demanding answers.
The Controversial Finale That Divided a Nation
When the 90-minute special aired in May 2021, expectations couldn't have been higher. After nine years and six series tracking AC-12's battle against police corruption, viewers expected a satisfying conclusion to the hunt for 'H'. Instead, they discovered the elusive fourth man was DSU Ian Buckells, played by Nigel Boyle - a revelation that disappointed even the cast.
Adrian Dunbar, who portrayed Superintendent Ted Hastings, confessed his frustration: 'When you find out it is this idiot, Buckles, it is so frustrating.' This sentiment echoed throughout the fanbase, who had invested years in the complex storyline.
Gaping Plot Holes That Need Explaining
The series six finale centred on AC-12's investigation into journalist Gail Vella's murder, which exposed a network of corrupt officers. While DCI Joanne Davidson was revealed to have orchestrated the killing and Buckells was unmasked as H, numerous questions remained unanswered.
One major confusion involved why H attempted to kill DCI Davidson after she'd effectively helped his cause by identifying former Chief Superintendent Patrick Fairbank as 'a bent copper'. This move temporarily diverted AC-12's attention from Buckells, making the attempted hit on Davidson seem counterproductive.
The logistics of how DI Steve Arnott and DI Kate Fleming intercepted the prison van transporting Davidson also left viewers scratching their heads. The scene showed Davidson being bundled into a fake prison van, only for Arnott to suddenly emerge as the driver after the vehicle passed under an underpass - with no explanation of how the switch occurred.
Character Arcs That Defied Logic
Perhaps most controversially, DCI Davidson was allowed to enter witness protection and start an idyllic new life in the countryside with her girlfriend, despite her involvement in multiple crimes including luring Fleming to a near-fatal shootout.
Meanwhile, personal relationships provided more questions than answers. Steve Arnott's close bond with Steph Corbett, widow of undercover officer John Corbett, seemed to be building toward romance until he discovered she'd lied about money given to her by Hastings. His professional partnership with Fleming also hinted at potential romance when she told him: 'You don't know what you've got 'til it's gone.'
The Future of AC-12 and Unresolved Mysteries
Despite finally identifying H, AC-12 found itself weakened by restructuring and internal struggles. Arnott battled painkiller addiction, Hastings faced forced retirement after confessing to inadvertently revealing Corbett's undercover status, and the unit's powers were significantly reduced.
Critical questions about the organised crime group's leadership remain unanswered. Buckells pinned blame on Tommy Hunter, who died in series two, leaving open the possibility that another corrupt officer still pulls the strings.
Other mysteries include who forged Fleming and DS Chris Lomax's signatures to access Davidson's prison cell, whether Chief Constable Osborne is corrupt after consistently dismissing AC-12's corruption findings, and what role Steph Corbett might still play in the ongoing drama.
As Line of Duty prepares for its return after five years, creator Jed Mercurio faces the challenge of addressing these lingering questions while delivering the satisfying conclusions that 17 million viewers deserve.
