Jed Mercurio has a thing for making us feel incredibly uneasy. By the time we hit Line of Duty Season 5, that feeling wasn't just a low-level hum; it was a full-blown siren. You remember the tension. You remember the balaclava men. Most of all, you remember Stephen Graham looking like he was about to explode in every single frame.
It’s been years since it first aired on BBC One, but this specific stretch of episodes remains the high-water mark for many AC-12 purists. Why? Because it flipped the script. Usually, we're watching Ted Hastings, Kate Fleming, and Steve Arnott look at monitors and interview suspects in that iconic glass box. But Season 5 took us into the dirt. It gave us John Corbett.
The Undercover Nightmare of John Corbett
Stephen Graham's performance as DS John Corbett is probably the best thing to ever happen to the show. Honestly. He wasn't just a "bent copper" or a standard villain. He was a man who had gone so far under that the surface didn't exist anymore.
Corbett was embedded in the OCG (Organised Crime Group), and the line between "doing what’s necessary" and "becoming the monster" was basically non-existent. Think about that scene with the raid on the police transport. It was brutal. It was fast. It felt real because Graham played Corbett with this desperate, vibrating energy that suggested he knew he was already dead.
Most shows treat undercover work like a cool spy movie. Line of Duty Season 5 treated it like a slow-motion car crash. You’ve got Maneet Bindra—poor, compromised Maneet—caught in the middle of a game she was never equipped to play. Her death early in the season was a massive "oh no" moment that signaled Jed Mercurio wasn't playing around. He was clearing the board.
The brilliance of this season lay in the ambiguity. Was Corbett actually trying to take down "H"? Or had he just lost his mind? When he’s standing in Ted’s wife’s kitchen, the stakes aren't just about police procedure anymore. It’s personal. It’s terrifying.
Ted Hastings and the Letter H
For years, we trusted Ted. "Like battle, like boy," "mother of God," and "the letter of the law." He was our moral compass. Then Line of Duty Season 5 decided to break that compass and throw it in the trash.
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Suddenly, we’re looking at Ted’s laptop being disposed of at a specialized facility. We’re seeing him visit Lee Banks in prison without a witness. We’re seeing the £50,000 in the envelope. For the first time, Steve and Kate—and the audience—had to ask if the man leading the charge against corruption was actually the source of it.
It was a bold move. Some fans hated it. They felt like the show was betraying Ted's character just for a twist. But if you look closely at Adrian Dunbar’s performance, the nuance is incredible. He’s playing a man who is broke, lonely, and desperate, making him exactly the kind of person the OCG targets. He’s not necessarily evil; he’s just human. And in the world of AC-12, being human is a liability.
The interrogation of Ted Hastings in the final episode is a masterclass. Seeing him on the other side of the table, being grilled by Patricia Carmichael (Anna Maxwell Martin, who is delightfully condescending), was peak television. Carmichael is the foil Ted deserved. She doesn't care about his catchphrases or his history. She sees a man with a laptop and a bag of cash.
The OCG and the Balaclava Men Explained
One thing people often get wrong about this season is the identity of the "Balaclava Man." People kept looking for one guy. But Season 5 made it clear: there isn't one guy.
The Balaclava Men are a collective. They are the foot soldiers of a massive, sprawling criminal enterprise that reaches into every corner of the police force. This season widened the lens. We saw the links back to Season 1 (the tragic history of John Corbett’s mother in Belfast) and realized this wasn't just about a few bad apples in London. This was a decades-long conspiracy.
Tommy Hunter. Lindsay Denton. The Caddy. All these threads started to pull together.
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What Really Happened with the "H" Reveal?
Okay, let’s talk about the ending of Season 5 because it still causes arguments at pubs across the country. The realization that "H" wasn't a name, but a sign.
The dying declaration of Matthew "Dot" Cottan was re-examined. Steve Arnott realized that Dot wasn't trying to say a name starting with H. He was using Morse code with his fingers. Four dots. Four "H"s. Four high-ranking officials in league with the OCG.
It felt a bit like a reach to some. You might think, "Really? Morse code?" But in the context of the show’s obsession with tiny details and forensic evidence, it fit. It meant the hunt wasn't over. It meant that while Gill Biggeloe was caught, there were still shadows in the hallway.
Gill Biggeloe was a great reveal, by the way. Polly Walker played her with such smooth, legalistic venom. She was the perfect example of how the OCG doesn't just use thugs; they use lawyers, fixers, and high-level bureaucrats.
Why Season 5 Changed the Show Forever
Before this season, Line of Duty was a procedural with a seasonal arc. After Season 5, it became a sprawling epic. The stakes moved from "who killed this person?" to "is the entire institution of policing fundamentally broken?"
It also changed how we view the core trio. Steve’s back injury and his burgeoning pill addiction, Kate’s promotion and the strain on her home life, and Ted’s fall from grace. They weren't just the "good guys" anymore. They were survivors.
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The pacing was relentless. One minute you're watching a tense tactical operation, the next you're in a 20-minute dialogue scene that feels even more dangerous. That is the Mercurio magic. He knows that a word spoken in an interview room can be more lethal than a bullet in a dark alley.
Misconceptions and Little Details You Missed
- The Laptop: People still ask what was on it. While the show implies Ted was looking at pornography or trying to communicate with the OCG to bait them, the reality is it was a symbol of his compromised state.
- Lisa McQueen: Many thought she was undercover too. She wasn't. She was a true believer who eventually found a way out. Her survival was a rare moment of "mercy" in a show that usually kills off its best side characters.
- The Belfast Connection: This is crucial. Corbett's motivation was rooted in the death of his mother, Anne-Marie McGillis, an informant who Ted Hastings knew during his time in the Royal Ulster Constabulary. This link added a layer of historical weight to the corruption.
The show isn't just about "catching the baddie." It's about the "grey area." Corbett was a "good" cop who did "bad" things. Ted is a "good" cop who made "bad" mistakes. The OCG are "bad" people who are very "good" at exploiting those mistakes.
How to Re-watch Like an Expert
If you're going back to watch Season 5, don't just focus on the action. Watch the background characters. Watch the way the "UCO" (Undercover Officer) protocols are handled—or mishandled.
- Follow the money: Keep an eye on the £50k. It moves through different hands and tells the story of Ted's desperation better than any monologue.
- Listen to the silence: The best moments in Season 5 are when characters don't speak. The look on Kate’s face when she realizes Ted might be lying to her is devastating.
- Check the dates: The timeline of Corbett’s mother’s disappearance and Ted’s service in Northern Ireland is the "skeleton key" for the emotional core of the season.
The real takeaway from Line of Duty Season 5 is that nobody is bulletproof. Not even the people we want to believe in most. It forced the audience to stop being passive viewers and start being investigators themselves.
To truly grasp the complexity, look into the real-world history of "supergrass" informants and undercover operations in the UK. The show draws heavily from the atmosphere of the Stevens Inquiries and the complex history of policing during the Troubles. This isn't just fiction; it's a dramatization of how power curdles when it's kept in the dark for too long.
Now, go back and watch the first episode of the season again. Knowing what happens to Corbett makes his initial bravado feel like a heartbreaking mask. That’s the mark of a great story: it changes every time you see it.
Actionable Insights for Fans
- Track the "H" Clues: Re-watch the Season 3 finale alongside Season 5. Compare Dot Cottan’s hand movements with Steve’s later analysis. It’s a rewarding bit of forensic viewing.
- Analyze the Interview Techniques: Research the "PEACE" model of interviewing used by UK police. You’ll see exactly where Patricia Carmichael deviates from it to rattle Ted.
- Explore the Cast’s Other Work: To see the range of these actors, watch Stephen Graham in The Virtues or Anna Maxwell Martin in Motherland. It highlights just how transformative their roles in Line of Duty really were.