8.4/101,477 votes#1 - Episode 1
Season 4 Episode 1 - Aired 3/26/2017
DCI Roz Huntley is under intense pressure from her superiors to apprehend a serial murderer after months of fruitless investigation.
Director: Jed Mercurio
Writer: Jed Mercurio
8.1/101,246 votes#2 - Episode 2
Season 4 Episode 2 - Aired 4/2/2017
AC-12 crank up their investigation into Operation Trapdoor. Kate makes progress in her undercover role.
Director: Jed Mercurio
Writer: Jed Mercurio
8.6/101,329 votes#3 - Episode 3
Season 4 Episode 3 - Aired 4/9/2017
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.
Director: John Strickland
Writer: Jed Mercurio
8.5/101,272 votes#4 - Episode 4
Season 4 Episode 4 - Aired 4/16/2017
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.
Director: John Strickland
Writer: Jed Mercurio
8.5/101,231 votes#5 - Episode 5
Season 4 Episode 5 - Aired 4/23/2017
DCI Roz Huntley struggles to allay her husband's suspicions. AC-12 find a new angle to pursue their case against her.
Director: John Strickland
Writer: Jed Mercurio
9.0/101,526 votes#6 - Episode 6
Season 4 Episode 6 - Aired 4/30/2017
While Nick Huntley faces lengthy questioning, AC-12 remain convinced of Roz's involvement.
Director: John Strickland
Writer: Jed Mercurio
Season 4 Ratings Summary
"Episode 1" is the best rated episode of "Line of Duty" season 4. It scored 8.4/10 based on 1477 votes. Directed by Jed Mercurio and written by Jed Mercurio, it aired on 3/26/2017. This episode is rated 0.3 points higher than the second-best, "Episode 2".