The Undeclared War is a British near-future thriller television mini-series, aired from 30 June 2022 on Channel 4. The series is written by Peter Kosminsky.^[1][3][4]

The series follows two main characters, Saara Parvin in the UK and Vadim Trusov in Russia, during a cyber and misinformation attack upon the UK.

Parvin has just started a one-year student-placement at GCHQ when a cyber-attack takes down some of the UK-internet and she joins the team examining the code of the malware. She is praised when she discovers a second attack within the code and a diligent search for a third attack doesn't find one.

Meanwhile, she feels alienated within GCHQ but makes friends with John Yeabsley who spends his lunch-time correcting the grammar of other people's blogs. He, in turn, says how alienating it is to not be able to talk about his work outside. We later find that Parvin hasn't told her family where she is working and her brother is appalled when she finally tells him.

Trusov had attended a class with Parvin in London and when he returns to Russia he starts working for Russia's twitter-misinformation campaign but when the UK crash the facility as reprisal for the malware he reluctantly joins the offensive malware department.

Russia escalates the attack and incites unrest in the UK by interfering with the reporting of a general election whereupon the UK remotely destroys some Russian arms dumps. Russia exaggerate the damage and uses it as a pretext for isolating GCHQ from NSA by leaking NSA software from a UK site.

Trusov eventually reveals that this was all planned by Russia and he deliberately and openly leaks all the Russian software to GCHQ as a gift that the UK can use to appeal for help from the USA just as the tit-for-tat reprisals become overtly physical. In the last scene, Parvin stands stricken with grief because Trusov has sacrificed himself.

• Hannah Khalique-Brown as Saara Parvin
• Simon Pegg as Danny Patrick
• Maisie Richardson-Sellers as Kathy Freeman (NSA employee detailed to GCHQ)
• Edward Holcroft as James Cox
• Adrian Lester as Prime Minister Andrew Makinde
• Alex Jennings as David Neal
• Mark Rylance as John Yeabsley
• Alfie Friedman as Gabriel Davies
• Kerry Godliman as Angie McMurray
• German Segal as Vadim Trusov
• Joss Porter as Phil
• Tinatin Dalakishvili as Marina Veselova

In the United States, the series was released on Peacock.^[1][6]

The global cyber-security firm NCC Group were consultants to the show. They developed the on-screen code whilst advising on and producing the mock-ups for the wider technical visuals.