A single sentence jotted on the back of an envelope in a public lavatory after a solitary dinner in Mayfair: “I had paid my last farewell to Harry a week ago, when his coffin was lowered into the frozen February ground, so that it was with incredulity that I saw him pass by, without a sign of recognition, among the host of strangers in the Strand.” Shortly thereafter, the film producer Alexander Korda asked Graham Greene to turn his sentence into a screenplay. It was 1947, and Korda wanted the picture set in Austria—he had money there that he couldn’t get out, due to currency restrictions—so he gave Greene $700 to go to Vienna. Korda, Greene, and director Carol Reed had just adapted Greene’s story The Fallen Idol, which would win the BAFTA for best British film in 1948, and Greene was on the verge of his first great literary success after more than two decades of modest esteem and spotty sales. The Heart of the Matter would sell more than 300,000 copies, liberating Greene from his a day job as an editor and rendering him a perennial candidate for the Nobel Prize he never won.
Vienna was full of rubble and split into four zones by the occupying French, British, American, and Soviet armies. The Hotel Sacher, where Greene put up, had its kitchen supplied with meat and vegetables from the black market while much of Vienna was still on meager rations. Scouting the city for settings, Greene hit on the large central cemetery for the opening scene. He learned of men who moved through Vienna’s sewers, smuggling adulterated penicillin. He met with spies, including the double agent Peter Smollett, a Times of London correspondent working for the Russians, and played a practical joke on the visiting Elizabeth Bowen by predicting a police raid at the nightclub where they were drinking that he had in fact arranged with a British officer. Add to all this a friendship betrayed and a love triangle and you have an archetypal Greene plot.