The Undeclared War — US release date, teaser, cast, plot and everything we know

The Undeclared War first look image
The Undeclared War follows a team of GCHQ analysts as they attempt to ward off a series of cyber attacks on the UK. (Image credit: Channel 4)

The Undeclared War is a British cyber-thriller that has already aired in the UK but is heading to the US via the NBCUniversal streaming service, Peacock.

Directed and co-written by seven-time BAFTA-winner Peter Kosminsky (Wolf Hall, The Government Inspector), The Undeclared War is a groundbreaking mini-series set in the near future that wants to shine a light on the very real threat that cybercrime poses to the world. 

Here’s everything you need to know about The Undeclared War...

The Undeclared War release date

The Undeclared War premiered on Channel 4 and All4 on Thursday, June 30 at 9 pm; all six episodes have now aired on TV but they're available to stream on-demand on All4.  

The series is heading to the US as a Peacock Original, meaning Peacock Premium customers will be able to stream the new show from August 18.

How many episodes are there in The Undeclared War?

The Undeclared War is a six-part miniseries; each of the six episodes is roughly 45-55 minutes long.

The Undeclared War cast 

The Undeclared War has a star-studded cast lined up. Simon Pegg (Hot Fuzz, Mission: Impossible) plays GCHQ’s Head of Operations, Danny Patrick. Oscar-winning actor Mark Rylance (Bridge of Spies) also stars as John Yeabsley, a retired Cold War veteran who’s brought back to GCHQ to help combat the new threat to Britain. 

Adrian Lester (Trigger Point, Mary Queen of Scots) plays Andrew Makinde, the UK’s first Black Conservative Prime Minister, with Maisie Richardson-Sellers (Star Wars: The Force Awakens) featuring as American cyber-analyst Kathy Freeman who's on attachment at GCHQ from the NSA.

Finally, Alex Jennings (The Crown) features as Head of GCHQ David Neal, with newcomer Hannah Khalique-Brown on board as Saara Parvan, a young student doing work experience in GCHQ’s Malware Department. 

Additional cast includes Edward Holcroft (Kingsman), German Segal (The Red Ghost), Tinatin Dalakishvili (Medea), Hattie Morahan (Operation Mincemeat), Ed Stoppard (Brave New World) and Kerry Godliman (After Life).

What is The Undeclared War about? 

The Undeclared War is set in post-pandemic Britain in 2024 and follows a crack team of data analysts working at GCHQ who are trying to fight off a potential cyber-attack on the UK electrical system.

Kosminsky says: “The series is based deep within the least-known arm of the UK’s intelligence infrastructure, GCHQ. The story we’re now able to tell casts an extraordinary, revelatory light on the hot, undeclared war taking place right now in the world’s newest and most invisible domain of conflict — cyber.”

During a three-year research process, Kosminsky and his team gained access to the cybersecurity industry on both sides of the Atlantic to ensure they could create a realistic picture of the threat posed by cybercrime to the Western world.

The official Channel 4 plot summary also offered up way more detail about the story. It reads: "Set in 2024, The Undeclared War tracks a leading team of analysts buried in the heart of GCHQ, secretly working to ward off a series of cyber-attacks on the UK in the run-up to a general election. When a routine stress test of internet infrastructure goes awry 21-year-old GCHQ intern Saara Parvin (played by Hannah Khalique-Brown) suddenly finds herself operating on the invisible frontier of high-stakes cyber warfare. 

In a thrilling cat and mouse game, Saara and the team at GCHQ must try to stay one step ahead and anticipate their opponents' every hidden move. The clock is ticking as a battle with high stakes and unpredictable enemies take place entirely online, with very real consequences. But how do you win a war most of the public don’t know you’re fighting?"

Is there a trailer? 

On June 10, Channel 4 released a stunt film to kick off promotion for the new series.

Filmed in the style of an emergency governmental broadcast, the 100-second film sees Daniel Patrick (Simon Pegg) and Prime Minister Andrew Makinde (Adrian Lester) broadcasting from GCHQ and warning the public of an imminent cyber attack. You can see it below: 

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Peacock has since debuted a proper trailer for the show which gives you a clearer idea of what to expect from the show:

How many seasons of The Undeclared War are there?

There's on been one full season of The Undeclared War so far, and so far, we haven't had any news about the potential for a follow up, so right now, there's just this first season to enjoy.

That being said, the ending definitely left a few questions unanswered, so there's still a chance the show could return later down the line: as soon as we know more, we'll be sure to update this guide!

Martin Shore
Staff Writer at

Martin is a Staff Writer with, where he produces a variety of articles focused on the latest and greatest films and TV shows. 

Some of his favorite shows are What We Do In The Shadows, Bridgerton, Gangs of London, The Witcher, Doctor Who, and Ghosts. When he’s not watching TV or at the movies, Martin’s probably still in front of a screen playing the latest video games, reading, or watching the NFL.