Series 4
2017 · 6 episodes · 5h 54m in all · 8.4/10
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.

Episodes

1. Episode 1
26 Mar 2017 · 58 min · 8.1/10
DCI Roz Huntley is under intense pressure from her superiors to apprehend a serial murderer after months of fruitless investigation.

2. Episode 2
2 Apr 2017 · 60 min · 8.1/10
AC-12 crank up their investigation into Operation Trapdoor. Kate makes progress in her undercover role.

3. Episode 3
9 Apr 2017 · 60 min · 8.4/10
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
16 Apr 2017 · 59 min · 8.4/10
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
23 Apr 2017 · 59 min · 8.3/10
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
30 Apr 2017 · 58 min · 8.8/10
While Nick Huntley faces lengthy questioning, AC-12 remain convinced of Roz's involvement.
Line of Duty Series 4: quick answers
How many episodes are in Line of Duty Series 4?
Series 4 of Line of Duty has 6 episodes, about 6 hours in total.
When did Line of Duty Series 4 come out?
Series 4 premiered on 26 Mar 2017.
What is the best episode of Line of Duty Series 4?
By viewer score, episode 6, “Episode 6”, at 8.8/10.