This work investigates the clandestine intelligence operations conducted between British businessman Greville Wynne and Soviet Colonel Oleg Penkovsky during the height of the Cold War. Greville Wynne, the author and primary participant, provides a firsthand account of his recruitment by MI6 to act as a courier for Penkovsky. The text argues that these intelligence exchanges were critical in providing the West with information regarding Soviet nuclear capabilities and intentions during the Cuban Missile Crisis.

Historians and intelligence scholars frequently cite this memoir as a primary source for understanding the operational realities of human intelligence during the 1960s. Readers often note the candid, albeit subjective, nature of Wynne's prose regarding his imprisonment and interrogation.