The Undeclared War is worrying - let’s hope the real GCHQ is better prepared for a cyberattack

“Our nation is under threat of imminent cyber attack. We have reason to believe this attack, by an as-yet unidentified foreign power, will be far more damaging and wide-ranging than anything we have seen before. We must all immediately prepare ourselves for the impact of this invisible strike.” These are words you don’t particularly want to hear your Prime Minister say in a live emergency broadcast just as you settle in to eat your Friday night curry in front of Celebrity Gogglebox.

But that’s exactly what happened at the start of June, when Adrian Lester appeared on our TVs, posing as fictional PM Andrew Makinde, alongside Simon Pegg as GCHQ boss Daniel Patrick. Never mind that they’re two of the most recognisable actors in Britain, many viewers were panicked by the advert for Peter Kosminsky’s (Wolf Hall) new Channel 4 drama, The Undeclared War, and Ofcom has been asked to investigate. Now, it’s time to see what all the fuss is about.

The series – streaming in full on All 4 or airing weekly on Thursday evenings – follows the tug of war between a cautious, considered GCHQ and a kneejerk government facing public scrutiny as Britain suffers an unexpected cyber attack from an unknown aggressor. It’s well-trodden ground for Kosminsky, who’s previous work has taken in the Iraq War (The Government Inspector), the Lašva Valley case (Warriors) and the Israel-Palestine conflict (The Promise). No matter how celebrated he is – in 1999 Bafta awarded him for his “Outstanding Creative Contribution to TV” – Kosminsky is a writer unafraid to needle even the most delicate of political situations.

We see most of the action through the eyes of Saara Parvin (newcomer Hannah Khalique-Brown), a bright but reserved student who heads to GCHQ on work experience, though she suspects her placement has more to do with her ethnicity than her talent. “I hope that’s not why you picked me, because I’ve got a brown face,” she ventures with her chaperone when he laments the “pale, male and stale” state of GCHQ employees.

As she arrives at the offices, a cyber attack is launched on the UK’s internet and the intelligence agents head to their battle stations. As you can imagine, there’s not exactly a lot Saara is trusted with at this point, but while playing around with the offending malware in a sandbox programme she spots a piece of hidden code and alerts the team to a second imminent attack. As brilliant as Saara is, let’s hope the real GCHQ is a little more thorough and doesn’t miss threats easily found by an inexperienced student.

The Undeclared War could have easily been very boring – watching someone read through reams of code indecipherable to the average viewer does not make for very absorbing television. But Saara has an active imagination, prompting surrealist scenes reminiscent of Sherlock’s sprawling mind palace: as her brain rattles through the cipher we see her comb through libraries, unlocking doors and climbing stairs.

And it’s not just about the attack – as in any office, there are politics and personal grievances to contend with. While Saara is shunned by her new co-workers (until she makes the breakthrough), there’s also a tension between the GCHQ employees and the solo NSA representative who has the admittedly awful job of liaising between the British and US intelligence agencies. It’d be a far too recognisable workplace drama, if the problem at hand weren’t so extreme.

Lester and Pegg put in admirable performances as uptight political power players who, despite their very different ideas about how to protect Britain, are ultimately on the same side. But it’s Khalique-Brown who steals the show.

Saara is quiet, maybe even emotionally stunted, only expressing herself with force when her depressive father – the only person in her family who knew about her GCHQ placement – dies. It’s here that the series shows its emotional side, interrogating the experience of a young British-Asian woman who is underestimated by those around her and with ambitions beyond those expected of her.

Broad in scope and rarely letting go of its in-built tension, The Undeclared War feels like a fresh take on political drama. That by the end of the series we may be none the wiser as to how a cyber attack really works doesn’t matter – it seems that no-one in the room where it happens is too sure either. Now that’s a terrifying prospect.

The Undeclared War box set is streaming on All 4 now. The first episode airs tonight, Thursday 30 June, at 9pm on Channel 4.