Line of Duty Season 4 Episodes

Find out where to watch Season 4 of Line of Duty tonight

Season 4 Episode Guide

Episode 1 - Episode 1

In a career-defining case, DCI Roz Huntley is under intense pressure from her superiors to apprehend a serial killer after months of fruitless investigation. When another victim is abducted, Roz is on the scene to track down and charge a 24-year-old man. But doubts around the young man's guilt lead Chief Forensic Investigator Tim Ifield to alert AC-12 to a possible miscarriage of justice.


Episode 2 - Episode 2

A dismembered body is discovered and DCI Roz Huntley fails to report for duty. AC-12 crank up their investigation into Operation Trapdoor, concerned that Michael Farmer will go to jail for crimes he didn't commit. With suspicions growing that Roz withheld crucial evidence, a new DCI is drafted to run Operation Trapdoor. Kate makes progress in her undercover role, but AC-12's investigation falters when they realise that their main informant has also gone missing.


Episode 3 - Episode 3

AC-12 wrestle with new forensic evidence casting doubt over Tim Ifield and another woman approaches Kate claiming to have been assaulted by Michael Farmer. Steve fumes over the contradictory testimony, while Kate ingratiates herself with the Trapdoor team. Roz's husband Nick is challenged to vouch for his wife's whereabouts on the night Tim Ifield went missing.


Episode 4 - Episode 4

Roz's husband Nick is brought in for questioning by AC-12. While Nick denies any involvement in Steve's attack, his suspicion of Roz grows. Meanwhile, AC-12 discover new anomalies in the forensic evidence and issue DCI Roz Huntley with a second Reg 15 notice. AC-12's case appears airtight until Roz fights back with some inside information of her own.


Episode 5 - Episode 5

DCI Roz Huntley's health and marriage continue to deteriorate, as Nick's suspicions over his wife's guilt continue to grow. Despite being recused from investigating Roz by ACC Hilton, a cold case gives AC-12 a new angle to challenge Roz.


Episode 6 - Episode 6

While Nick Huntley faces lengthy questioning over his role in Tim Ifield's murder, AC-12 remain convinced of Roz's involvement. But with Nick about to be charged and Hastings under threat from ACC Hilton, has their time run out? As the truth emerges and officers risk everything in the line of duty, who among them will escape unscathed?


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