In July 1949, and again in January 1950 the U.S. Atomic Energy Commission shipped useful amounts of the short-lived isotope phosphorus-32 to a sanatorium in Trieste, Italy. They were used to treat a patient who had a particularly malignant kind of brain tumor. This distribution of isotopes abroad for medical and research purposes was hotly contested by Commissioner Lewis Strauss, and led to a bruising confrontation between him and J. Robert Oppenheimer. This paper describes the debates surrounding the foreign isotope program inside the Commission and in the U.S. Congress. In parallel, it presents an imagined, but factually-based story of the impact of isotope therapy on the patient and his doctor in Trieste, a city on the Italian-Yugoslavian border that was at the heart of the cold war struggle for influence between the U.S. and the USSR. It weaves together the history of science, institutional history, diplomatic history, and cultural history into a fable that draws attention to the importance of the peaceful atom for winning hearts and minds for the West. The polemics surrounding the distribution of isotopes to foreign countries may have irreversibly soured relationships between Oppenheimer and Strauss, and played into the scientist's loss of his security clearance. But, as those who supported the program argued, it was an important instrument for projecting a positive image of America among a scientifc elite abroad, and for consolidating its alliance with friendly nations in the early years of the cold war——or so the fable goes.