Rachel Carey
- Played by: Holliday Grainger
A young officer who has been promoted to run Shaun Emery's case, before planning on going back to counterterrorism.
- Aloof Big Sister: A very generally aloof one, especially to her teenage half-sister.
- Big Good: She ultimately is the one—with help from many others—to expose the Correction Program and the UK-based conspirators.
- Break the Haughty: She's getting there, but only really loses it once she is shown what is really in Frank Napier's house.
- Go-Getter Girl: She's only supposed to be on short-term secondment to the Murder Squad, and she wants to become DI.
- Know-Nothing Know-It-All: She has a streak of this, denying that she is a Naïve Newcomer when she clearly is.
- The Mistress: To her married boss at SO-15.
- Sleeping Their Way to the Top: Danny accuses her of this, which she denies.
- Smug Smiler: A mostly heroic example, but her smug smile is her favorite way to bluff everyone, from Shaun to her bosses.
- Standard Cop Backstory: Dysfunctional home life, a pathological liar father, dead mother.
Shaun Emery
- Played by: Callum Turner
A once-disgraced soldier who is accused of kidnapping Hannah Roberts after being freed from prison.
- Digging Yourself Deeper: His insistence on going to Hannah's house only gets him in even more trouble.
- Hair-Trigger Temper: Shaun is extremely hostile and tightly wound.
- Hero with Bad Publicity: The end of the first season has Shaun being forced to admit to the public that he accidentally killed Hannah and the unarmed Taliban fighter in Afghanistan.
- Lower-Class Lout: Shaun is from a rough background, working-class, and aggressive.
- Morality Pet: His young and beloved daughter, Jaycee.
- My God, What Have I Done?: Shaun visibly worries that he could have hurt Hannah, and has a meltdown when he sees the tape showing that he did.
- Papa Wolf: He goes absolutely crazy when he learns that his daughter has been kidnapped.
- Raised by Grandparents: Shaun only lives with his grandfather.
- Shell-Shocked Veteran: Shaun clearly suffers from PTSD from his tour in Helmand, Afghanistan, having bad dreams, flashbacks, and severe aggression.
- Unreliable Narrator: Claims that Hannah got on the bus. Which she did.
Commander Danny Hart
- Played by: Ben Miles
Rachel's once-boss, a very well-connected officer.
- Love Makes You Dumb: His attraction to Rachel means that he gives her far more information than he should; it's even him that tells her about "correction".
- May–December Romance: He's significantly older than Rachel.
- Silver Fox: Part of the attraction between he and Rachel, or so it seems.
Hannah Roberts
- Played by: Laura Haddock
Shaun Emery's barrister.
- Not Quite Dead: She did get on the bus. Not that she was alive for much longer after that.
- Uptown Girl: A posh barrister to Shaun's lower-class soldier.
- Well-Intentioned Extremist: She genuinely wants to help Faisal and prove that law enforcement faked evidence so that he can arrested.
Charlie Hall
- Played by: L Barry Ward
Shaun's solicitor.
- Well-Intentioned Extremist: Like Hannah, he also wants to prove that law enforcement faked evidence so that Faisal can arrested.
Frank Napier
- Played by: Ron Perlman
- Bad Boss: He's not very nice at all to his underlings, claiming that Eli deserves it for being a "traitor".
- The Cracker: He runs a whole team of them, in addition to being this himself.
- Four Eyes, Zero Soul: A killer and evil American, who constantly wears glasses.
- Pet the Dog: When the Correction programme is exposed to the public, he lets Carey go and doesn't lift a finger to help Garland arrest or detain her. It probably has something to do with Garland hacking his medical records, making him think he has terminal cancer and almost driving him to suicide so she could take over his operation.
- Serious Business: He doesn't take kindly to Rachel telling him that General Grant wasn't actually at the battle.
- The Spymaster: Operate a small team of NSA agents in the Greater London Area.
Jessica Mallory
- Played by: Famke Janssen
- Even Evil Has Standards: Jessica is angry at Frank for letting Eli compromise his activities and exposing the ONI.
