The romance ended for Hinton when the United States dropped the atomic bomb. In December 1948 she joined the communist Chinese cause, inspired by accounts of the communist struggle from her brother, author William Hinton, who was accused by McCarthyites of propagandizing “for the brain-washing, soul-killing Red Chinese.” She surfaced four years later at a Beijing peace conference to express “a deep sense of guilt and shame” for Hiroshima and to denounce the bomb as “a crime against humanity.” That appearance sealed her fate as a target of America’s anti-communist frenzy, and a life of exile. She and her husband spent 18 years in the hardscrabble countryside near Inner Mongolia before moving to a farm north of Beijing, where they still live in the shadow of the ’50s. Spry and white-haired at 77, Hinton holds up an old caricature from Real magazine, portraying her as a trench-coated femme fatale against a mushroom cloud background. The caption calls her a “Mata Hari trudging in Mongolian mud” who had “given her all to the reds.” Hinton laughs: “They just whipped up a spy scare, and the media wrote whatever they wanted.”

Though never formally charged with espionage, Hinton’s case drew intense scrutiny from the Senate Internal Security Subcommittee, which closely questioned her brother in July 1954. Nothing came of it. The U.S. Atomic Energy Commission said she never had a security clearance and had done work on a low-power reactor that was subsequently declassified. In China, Hinton says, she never worked on nuclear weapons: “Nobody had to help China with the bomb.”

Beijing’s real bomb builders were rewarded with lavish perks and apartments. By contrast, Hinton and her husband married in Mao Zedong’s preliberation stronghold of Yanan and helped the communists develop farm tools. “I made a donkey dump cart,” says Hinton. They remain ascetic Maoists. They are disappointed that 20 years of reform in China have handed over communal property to “capitalist compradores,” and that dairy products from the station’s 200 or so cows go to feed the customers of a distinctively American icon, McDonald’s.

Today Hinton is no longer a symbol of cold-war hostility. To one Western diplomat in Beijing she is merely a “granola-eating innocent from Vermont.” (Her family founded the Putney School there.) While many Chinese sympathize with Hinton’s travails, they, too, find her straitlaced Maoism curiously out of date. McCarthy-era scare-mongering did not always lead to such a benign ending in China. After the brilliant, MIT-trained scientist Qian Xuesen was interrogated by the FBI on suspicion of being a Communist Party member he returned home to become the father of China’s ballistic-missile arsenal, designing the Silkworm and M-9 missiles. “Almost all prominent McCarthy-era targets were hounded for their China policies,” says Qinghua University professor Xue Mouhong, a Chinese America-watcher and former diplomat. “But I’m sure the American people will not allow current tensions to become a second McCarthy period.” If there is at least one thing on which Washington and Beijing can agree, it is how far they’ve come since the first Los Alamos spy scares.