Line of Duty Season 4

Season 4

The fourth series sees AC-12 facing their most devious opponent yet! Under pressure from her superiors, DCI Roz Huntley charges a young man with a series of murders after months of fruitless investigation, but is he guilty? The Chief Forensic Investigator has doubts and turns to AC-12.

Air date: 2017-03-26

Episodes: 6

Episodes

E1: Episode 1

DCI Roz Huntley is under intense pressure from her superiors to apprehend a serial murderer after months of fruitless investigation.

Air date: 2017-03-26 • ★ 8.2

E2: Episode 2

AC-12 crank up their investigation into Operation Trapdoor. Kate makes progress in her undercover role.

Air date: 2017-04-02 • ★ 8.1

E3: Episode 3

As AC-12 wrestle with the new forensic evidence casting doubt over Tim Ifield, Kate is approached by another woman claiming to have been assaulted by Michael Farmer.

Air date: 2017-04-09 • ★ 8.4

E4: Episode 4

Roz's husband Nick is brought in for questioning by AC-12. But while Nick denies any involvement in Steve's attack, his suspicions about Roz mount.

Air date: 2017-04-16 • ★ 8.385

E5: Episode 5

DCI Roz Huntley struggles to allay her husband's suspicions. AC-12 find a new angle to pursue their case against her.

Air date: 2017-04-23 • ★ 8.231

E6: Episode 6

While Nick Huntley faces lengthy questioning, AC-12 remain convinced of Roz's involvement.

Air date: 2017-04-30 • ★ 8.846