Recruited in 1944 as an 18-year-old Harvard undergraduate to be the youngest physicist on the Manhattan Project, to create a bomb before the Germans did, Ted Hall didn’t share his colleagues’ elation after the successful detonation of the world’s first atomic bomb. Increasingly concerned during 1944—with Germany clearly losing the war—that a U.S. post-war monopoly on such a powerful weapon after the war could lead to nuclear catastrophe, he decided beginning that October to start passing key information about the bomb’s construction to the Soviet Union. After the war, at the University of Chicago, he met and married Joan, a fellow student with whom he shared a passion for classical music and socialist causes — and the explosive secret of his espionage. Living under a cloud of suspicion and years of FBI surveillance and intimidation, the pair raised a family while Ted refocused his scientific brilliance on groundbreaking bio-physics research. A Compassionate Spy reveals the twists and turns of this real-life spy story, and the couple’s remarkable love and life together during more than 50 years of marriage.