Series 4 Plot
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.
Line of Duty Series 4 aired on March 26th, 2017.
Watch 'Line of Duty' Series 4 Online
Series 4 Episodes
1. Episode 1
DCI Roz Huntley is under intense pressure from her superiors to apprehend a serial murderer after months of fruitless investigation.
2. Episode 2
AC-12 crank up their investigation into Operation Trapdoor. Kate makes progress in her undercover role.
3. 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.
4. 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.
5. Episode 5
DCI Roz Huntley struggles to allay her husband's suspicions. AC-12 find a new angle to pursue their case against her.
6. Episode 6
While Nick Huntley faces lengthy questioning, AC-12 remain convinced of Roz's involvement.
