The spy thriller "The Undeclared War" has returned for its second season on Channel 4, continuing its exploration of cyber warfare and government intrigue. The series stars Hannah Khalique-Brown, Simon Pegg, and Sian Brooke.

The latest season picks up with the fate of the UK resting in the hands of a power-mad Foreign Secretary, Richard Marston, portrayed by Ed Stoppard. In a dramatic turn, the Prime Minister, previously played by Adrian Lester, is depicted as being "incommunicado" at Camp David, the U.S. President's official retreat, rendering him unreachable even in a national crisis.

Marston is shown in the operations room at GCHQ, the government's cyber-listening post, reacting to apparent intelligence of Russian bombers heading for London. His immediate call for a "retaliatory attack on the military base in Kaliningrad" draws comparisons to the flamboyant pronouncements of DJ Kenny Everett.

The series employs a distinctive visual style, including an opening sequence filmed in a single, uninterrupted shot. This technique, reminiscent of the Netflix drama "Adolescence," requires intricate choreography and flawless dialogue delivery from the cast, as retakes are not an option. Director Paul McGuigan reportedly facilitated this by keeping many actors in static positions within their offices.

Simon Pegg stars as Danny, the Head of Operations at GCHQ, a character described as intensely dedicated to his job, to the point of sleeping in his work attire. The show's pacing and subject matter have been met with mixed critical reception, with one review suggesting that filing tax returns might be a more engaging activity for some viewers.

Despite criticisms of its narrative, "The Undeclared War" has been noted for its ambitious production, particularly the elaborate long-take opening. The series aims to keep viewers on edge with its high-stakes depiction of cyber threats and governmental responses.

Sian Brooke plays the role of a former spy and the wife of Simon Pegg’s character