The year is 1947. Moira Edwards Walker and her husband Thomas have settled into a normal life after adopting two orphaned Japanese girls who had been living in her cousin Margaret's home. But life does not remain ordinary. Abruptly, and without much explanation, Moira and Thomas leave their daughters in the care of Margaret and return to London where Moira, at Thomas' behest, becomes a "Watcher." She moves about Cambridge University and Highgate Cemetery where she photographs individuals who congregate near Karl Marx's statue. Amazingly, Moira does this without drawing attention to herself. Just as suddenly as the London work began, it ends. Moira and Thomas, now reunited with their girls, return to the United States and settle in Richland, Washington, near the Hanford Atomic Works. The two cousins maintain their connection through letter-writing, and for two years share thoughts on Moira's activities, the world's changing condition and Hanford, which has become a medical worry to Margaret. For Moira, Hanford becomes a world of intrigue that eventually puts her in the middle of international espionage. Many years later, Moira's daughter, Maemi, uses the letters written between her mother and her aunt to discover the secrets of that life. Letters from a Wary Watcher is a sequel to Letters from Brackham Wood, a book containing letters between the cousins that describe the years prior to and during WWII in both England and Spokane, Washington.