"Nestorian" Syriac-speaking Christians had established missionaries in China as early as 635, missionaries who were in fact encountered by Marco Polo toward the end of the thirteenth century. In 781, they erected 'Chingchiaopei', or the Luminous Teachings, a bilingual Syriac-Chinese monument with 2000 Chinese ideographs "carved with supreme skill in matchless Tang calligraphy". The monument is China's earliest record of Christianity. The quest to bring this "Nestorian" monument to the West is the narrative of this book.

The monument was discovered by native people in 1625, but the inscription stood abandoned and deserted for centuries. During "eleven rather strenuous months" in 1907 and 1908, Holm circumnavigated the globe in his attempts to interest Western institutions in the monument. A two-ton replica was ultimately displayed at the Metropolitan Museum of Art in New York for eight years, and later was given to the Lateran Museum in Rome where it still stands.

Holm vividly describes his expedition on caravans and houseboats. He talks of temples, synagogues and mosques; inns, houseboats and caves; common natives and Buddhist priests; prisoners, soldiers and guards.