It had all the hallmarks of a classic Cold War spy caper and it began in January 1958, when British intelligence's Moscow station delivered two rolls of microfilm into the hands of the CIA's Langley headquarters.
The films showed not the blueprints for a new Soviet warplane or ballistic missile, but something potentially more powerful in the ideological war between East and West: the complete Russian text of Boris Pasternak's masterpiece, Doctor Zhivago.
In a nine-point memo, marked secret but recently declassified, British intelligence said it was "in favour of exploiting the book", warning that Soviet censors were already putting pressure on Pasternak to put out a "revised" version.
And so began a covert CIA programme to press as many copies of Doctor Zhivago, banned in the Soviet Union, into the hands of as many Soviet citizens as possible as part of a political warfare campaign against the communists. The first chosen battleground was the 1958 Brussels Expo, where both the US and the USSR had built massive pavilions to showcase their competing ways of life.
About 130 recently declassified CIA documents form the basis for a new book, The Zhivago Affair: The Kremlin, the CIA and the Battle Over a Forbidden Book, which details the extraordinary lengths the agency took to infiltrate copies behind the Iron Curtain.
Internal memos warn that America's hand was "not to be shown in any manner" and document how the CIA collaborated with the Dutch intelligence agency to get a small academic house in The Hague to rush out 200 copies of the Russian text. Unable to distribute them directly at the US pavilion, the CIA instead handed them over to the Vatican pavilion, where Roman Catholic Russian emigres had "set up a small library 'somewhat hidden' behind a curtain" for Christians living under repressive regimes.
"There, the CIA-sponsored edition of Doctor Zhivago was pressed into the hands of Soviet citizens," said the authors, Peter Finn and Petra Couvee, a writer who teaches at St Petersburg State University in Russia. "Soon the book's blue linen covers were littering the fairgrounds. Some who got the novel were ripping off the cover, dividing the pages, and stuffing them in their pockets to make the book easier to hide."
But the runaway success of the plan also contained the seeds of its partial undoing as a curious literary world began to speculate that the CIA was behind the mysterious Russian edition.