'The Fourth Protocol' (1974) by Frederick Forsyth

'The Fourth Protocol' is a fast-paced espionage thriller blending Cold War tensions with an intricate plot of political subterfuge.

The story revolves around a Soviet conspiracy to destabilize the United Kingdom by exploiting its democratic system. The KGB, led by mastermind General Govorshin, devises "Plan Aurora," a scheme to detonate a small nuclear bomb in Britain and make it appear as though it was created by a rogue faction of British nuclear disarmament activists. The resulting public outrage would help elect a far-left government, aligning the UK with Soviet interests.

To execute this plan, the KGB enlists a skilled but ruthless operative, Major Valeri Petrofsky, who infiltrates the UK under deep cover. He begins assembling the nuclear device, relying on smuggled components and avoiding detection by MI5 and British law enforcement.

Meanwhile, John Preston, a sharp and independent-minded British intelligence officer, uncovers clues about Petrofsky's activities. Despite bureaucratic resistance and internal politics, Preston methodically pieces together the Soviet plot. The novel alternates between Preston's investigation and Petrofsky's covert operations, building tension as the two characters move closer to a dramatic confrontation.

The title refers to a secret clause in the Nuclear Non-Proliferation Treaty prohibiting the use of nuclear weapons to influence domestic politics, a clause the Soviets plan to violate.

In a thrilling climax, Preston thwarts the plot just in time, exposing Soviet machinations and averting a national crisis. The Fourth Protocol combines Forsyth’s signature attention to detail with a gripping exploration of Cold War espionage, political intrigue, and the threat of nuclear terrorism.