During the peak of Japanese imperialism, a doctor defies the fascist government and is arrested for treason. After a few days in prison, he declares his loyalty to the emperor and is released. This situation causes a rift between him and his young son, Yasushi. When Yasushi becomes a teenager, he enlisted in the Imperial Army and the man never sees him again. In 1939, he is conscripted to work in the Pingfang district of Japanese-occupied China. During the Second Sino-Japanese War, the Japanese biological research center was headquartered there. When he arrives at the research compound, he is struck by the lavishness of the accommodations compared to the stark poverty in the rest of the city. Soon, the doctors begin their work: experimenting on live Chinese prisoners. They infect them with diseases that are ravaging the Japanese army and tried to develop cures. The man remarks on the calm atmosphere; they all feel as if they are just treating patients as normal. During a routine prisoner transfer, he speaks with another doctor, S, who reveals that he’d stolen a crate of research documents. He plans to leak them and bring awareness to the medical genocide. After two years, that phase of the research ends. The Japanese government gives the doctor a small, rural clinic, which he still runs. After World War II ends, the United States gives all Pingfang doctors immunity in exchange to access to the research data. Thirty years later, the elderly man annually meets up with two other Pingfang colleagues. One year, they discover that S, who buried the documents in his backyard instead of exposing them, dug them up and hung himself. The men reflect on their own actions. They are stuck between blaming their superiors and blaming themselves.