Hahn was born in St. Louis and lived there until her family moved to Chicago during her high school years. She later attended the University of Wisconsin and in 1926 received the first mining engineering degree awarded to a female student. Following graduation, until the spring of 1927, she worked for an engineering firm in St. Louis and then as a company courier for that firm in Santa Fe, New Mexico. Returning to the East during the summer, she attended Columbia University for graduate work, taught geology during the 1927/28 academic year, and then headed for Europe on her first overseas tour. After living in Florence and London, she returned home briefly in 1929 before going to the Congo and two years' residence there. In 1932 she began further travels, finally settling in Shanghai in 1935 where she taught English for three years.

All during this decade of travel and adventure Hahn wrote almost continually--articles, stories, letters--and many of her pieces were printed in The New Yorker, as well as five full-length books being published. Fortunately, as a supplement to her writings, the collection also contains Hahn's letters home to her mother and family while she lived and traveled in Europe, Africa, and China. This early correspondence is particularly descriptive of people, places, and activities, and is most interesting for the early years of Asian conflict that would later be seen as a prelude of World War II. The Sino-Japanese conflict eventually caused Hahn to leave Shanghai for Hong Kong, where she was later forced to remain after the Japanese took over that area in 1941. She was finally repatriated in 1943 and proceeded to produce two books concerning those years: China to Me and Hong Kong Holiday. In 1945 Hahn married British Major Charles Ralph Boxer, 1904-2000, whom she had met in Hong Kong prior to his internment as a POW, and following the war they moved to his family home in England. She continued to write short fiction, articles for magazine publication, particularly The New Yorker, and a remarkable number of books. During the 1950's she ventured into the juvenile field with some fiction, juvenile biographies, and descriptions of some of the countries in which she had traveled or lived. Other publications include biographies of Aphra Behn, James Brooke, Fanny Burney, Chiang kai-shek, D.H. Lawrence, and Mabel Dodge Luhan; a description of the diamond business; four books on zoos and animals; histories of China, Ireland, women; and several autobiographical accounts.