Ben Macintyre's book recounts the dramatic 1982 defection of Vladimir Kuzichkin, a KGB officer stationed in Iran under the codename "Redwood," who had secretly begun spying for Britain's MI6. Kuzichkin's initial motivation was reportedly the hope that Western doctors could treat his sexual impotence, but as his posting neared its end MI6 tried to persuade him to stay embedded within the KGB rather than defect immediately, promising doubled pay and a future escape plan from Moscow. His eventual panicked flight illustrates the immense psychological toll of running a double agent inside a hostile intelligence service, and the story offers rare insight into Cold War-era espionage tradecraft.

Kuzichkin's MI6 handler, Ian McCredie, had struck a deal for him to remain in place and continue supplying intelligence after leaving Iran, but the strain proved unbearable — he was drinking heavily, sleeping badly and suffering recurring nightmares. When a cipher clerk mentioned that a security team was being sent from Moscow to tighten embassy procedures, Kuzichkin feared exposure and telephoned McCredie using a pre-arranged emergency code, demanding immediate exfiltration from Iran to the UK. McCredie, who had already scouted a weakness in border security for such a contingency, prepared to extract him under the noses of the KGB and Iran's Revolutionary Guard.