The call to missionary work comes in his last year in college, when he hears a visiting minister, John R. Mott, who is proselytizing for the Student Volunteer Movement For Foreign Missions, a liberal evangelistic organization.

At the 1907 China Centenary Missionary Conference in Shanghai, Treadup takes part in the debate between the older evangelists, who insist that their only mission is to spread the gospel, and the newly arrived missionaries of the Social Gospel persuasion like himself, who are convinced that their mission is good works, that is, the uplift of society through science, education, and social change.

Through the decade of the 1910s, Treadup organizes campaigns to introduce modern science to the educated men of the city in the hope that they will spread this knowledge down to the masses.

He uses posters, pictures, and scientific demonstrations to arouse interest among the audience, for instance a gyroscope, with which he performs impressive feats.

[3] At the start of the Second Sino-Japanese War Treadup, like the actual missionary Lewis Gilbert, witnesses the Nanking Massacre, and asks why God would allow such atrocities.

When war between the United States and Japan is declared in 1941, Treadup is imprisoned in the Weixian Internment Camp, as were many actual missionaries such as John Leighton Stuart.

[4] Hersey explains that the novel is a "fictional biography" in which the traits and experiences of Treadup are based on six actual missionaries, including his father, as well as G. Herbert Cole, C.H.

"[5] Many of the other characters are closely based on historical figures and most of the events depicted actually happened, although not necessarily in exactly the same order or to the analogous people.

The character Lin Fu-chen is much like Chang Po-ling, the founder of the Nankai Middle School in Tianjin, which was attended by Zhou Enlai, who plays a brief role in the book.

The distinguished American historian Arthur Waldron wrote that the novel is "a tale of lost faith and futility in the face of bland Chinese indifference to Western concerns...." He sees this theme especially at the novel's "tragicomic conclusion," when Treadup's son returns in an attempt to bury his parents' ashes, as they had wished, in Shanghai's Christian cemetery.

[5] When asked about the role of factual, historical research for the book as a novel, Hersey replied: An entire section of Treadup's journal is lifted verbatim, without attribution, from an actual letter written by William W. Lockwood, General Secretary of the Shanghai YMCA from 1903-1936.