The year is 1981. Tehran is in violent turmoil in the wake of the Iranian Revolution. The Soviets are planning to overthrow the Ayatollah’s fledgling Islamist regime. If they do so, one response from America – unknown to the public – would be to use nuclear weapons. Redwood is the story of how at the height of the Cold War, one mysterious double agent, whose intelligence reached the highest levels of British and American governments, cracked open the KGB, revealed the Kremlin’s secret plot and prevented Armageddon.

‘Redwood’ was the MI6 codename for this unsung, hitherto unknown hero of the Cold War, a highly-trained six-foot-four Russian intelligence officer who chose to expose the KGB’s deepest secrets, compelled to swap sides by a shaming secret of his own. Facing exposure, with both the Iranian Revolutionary Guards and his own KGB colleagues closing in, he demanded that MI6 try to smuggle him out of Iran in a high-stakes escape plan.

This is the gripping tale of one man’s courage, and its extraordinary unintended consequences that still shape our world today. It’s about a moving friendship between spies on opposite sides of the global conflict; about marriage, loyalty, betrayal and sexual dysfunction; and about how decisions made in secret can have huge, long-term ramifications.

Drawing on never-before-seen material from archives in multiple countries, and interviews with the participants including officers from MI6 and MI5, the KGB and CIA, Redwood combines the shadowy world of the Spy and the Traitor with the action of SAS: Rogue Heroes. It lifts the lid on an unknown and highly significant Cold War victory, on the machinations of history's Great Game, and on how espionage really works.

Without Redwood, our world would be very different – and might not exist at all.

Ben Macintyre is the multimillion-copy bestselling author of books including Colditz, Agent Sonya, SAS: Rogue Heroes, The Spy and the Traitor, Agent Zigzag, Operation Mincemeat and A Spy Among Friends. He is a columnist and Associate Editor at The Times, and has worked as the newspaper's correspondent in New York, Paris and Washington. Several of his books have been made into films and television series, including Operation Mincemeat, A Spy Among Friends and SAS: Rogue Heroes.