Line of Duty's AC-12 anti-corruption unit
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New to Line of Duty?

Six series, one long-running mystery, and a seventh series already filmed. Here's everything you need to know before you press play — no spoilers.

Jump to What It's About Where to Start The Guest Leads Where to Watch More for Fans FAQ

Streaming availability may change — check BritBox for current availability. Spoiler-free throughout, including no reveal of "H".

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What Is Line of Duty About?

Line of Duty follows AC-12, a fictional anti-corruption unit tasked with investigating police officers suspected of corruption from within their own force. Unlike most British mysteries, it isn't a new case in a new village each week — it's one long, tightly serialized story, with a running mystery about the identity of a corrupt senior officer known only as "H."

SettingFictional English police forces, filmed largely in Belfast
FormatSerialized, must be watched in order
First aired2012
Created byJed Mercurio, an original story (not based on books)
US ratingTV-MA on BritBox

Where Should a Beginner Start?

Start at the Very Beginning

Series 1, Episode 1 · 2012

There's no alternate entry point here — Line of Duty tells one continuous story, and Series 1 introduces the AC-12 trio, the format, and the case that sets everything else in motion.

Watch on BritBox →

The Guest Leads

Martin Compston, Vicky McClure, and Adrian Dunbar anchor AC-12 throughout, but each series brings in a new, high-profile guest lead as the officer under investigation.

Series 1–6

2012–2021

Lennie James, Keeley Hawes, Daniel Mays, Thandiwe Newton, Stephen Graham, and Kelly Macdonald have each led a series as the officer AC-12 investigates.

Series 7 (Coming 2027)

Filmed 2026 · Robert Carlyle joins

AC-12 has been disbanded and rebranded as the Inspectorate of Police Standards. Robert Carlyle joins as DC Shaun Massie, a Specialist Rifle Officer, opposite the returning core trio.


Where to Watch

All six series are available in order on BritBox in the US — watch them that way, since the story builds continuously.

Where to watch in the US

BritBox

All 6 series · Subscription required · Check current price at signup

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Free option: Not currently available free in the US

Streaming availability in the US can change. Check the linked service for the current season and episode selection.


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Frequently Asked Questions

Do I need to watch Line of Duty in order?

Yes. Unlike many British mysteries, Line of Duty builds one long-running story across all six series, with a returning cast of officers and an overarching mystery. Watching out of order will spoil major twists.

What does AC-12 mean?

Anti-Corruption Unit 12, the fictional police unit at the center of the show, tasked with investigating officers suspected of corruption within their own force.

Who are the main characters in Line of Duty?

DS Steve Arnott (Martin Compston), DI Kate Fleming (Vicky McClure), and Superintendent Ted Hastings (Adrian Dunbar) anchor AC-12 across all six series. Each series also brings in a new guest lead under investigation, played by a different well-known actor.

Who is "H" in Line of Duty?

The identity of H, a corrupt senior officer tied to organized crime, was one of British television's most talked-about mysteries and was resolved in the Series 6 finale. British TV Hub won't spoil it here — watch the show to find out.

How many series of Line of Duty are there?

Six series have aired so far (2012–2021), all streaming on BritBox in the US. A seventh series has finished filming and is expected to air in 2027.

Is Line of Duty coming back for a Series 7?

Yes. The BBC confirmed a seventh series, which finished filming in Belfast in mid-2026. Martin Compston, Vicky McClure, and Adrian Dunbar all return, joined by Robert Carlyle as the new guest lead, DC Shaun Massie. It's expected to air in 2027.

Where can I watch Line of Duty in the US?

BritBox is Line of Duty's main US streaming home, with all 6 series available.

Is Line of Duty based on real events or books?

No. It's an original creation by writer Jed Mercurio, a former hospital doctor who also created Bodyguard. He wrote every one of the show's 36 episodes himself.

Affiliate disclosure: British TV Hub is a participant in the Amazon Associates program and earns from qualifying purchases. Some links on this page may be affiliate links to BritBox. This never affects the recommendations — these are genuine editorial favourites.

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