The Soviets have developed a revolutionary new jet fighter, called 'Firefox'. Worried that the jet will be used as a first-strike weapon—as there are rumours that it is undetectable by radar—the British send ex-Vietnam War pilot, Mitchell Gant on a covert mission into the Soviet Union to steal the Firefox.
Led by Kim Philby, Plan Aurora is a plan that breaches the top-secret Fourth Protocol and turns the fears that shaped it into a living nightmare. A crack Soviet agent, placed under cover in a quiet English country town, begins to assemble a nuclear bomb, whilst an MI5 agent attempts to prevent it's detonation.