On April 9, 1831, three renowned surgeons at Guy’s Hospital in London performed a surgery on a Chinese patient named Hoo Loo, removing a massive tumor weighing 56 pounds. The operation took one hour and forty-four minutes and was carried out without anesthesia. Hoo Loo lost consciousness several times and eventually died on the operating table at the age of 32. This book takes Hoo Loo’s transnational medical case as its narrative thread, centering on an event that unfolded just before the Opium War, at a time when Britain was attempting to use Western medicine as a means to open the door to China. Drawing on a wealth of primary sources from both China and abroad, the author vividly captures the shock this incident provoked, particularly its lasting impact on British politics and the history of modern surgery. Through this lens, the book explores Sino-British relations, medical progress, medical ethics, and perceptions of the East in the political, diplomatic, scientific, and cultural domains.