Fatal Arithmetic in Kirin Alley

In the late autumn of 1935, a bizarre murder occurred in the "Juxian Building" of Changsan's residence in Qilin Lane, the junction of the Japanese Concession and the Chinese Concession in Tianjin. Cao Huan, a mysterious businessman who could control smuggling routes in North China, was poisoned and died at a banquet for celebrities from China and Japan. Shen Yan, a young special high-tech agent who was pushed out to take the mine, got a clue from the abnormal wear and tear on the deceased's cuffs - Cao Huan was not a businessman, but a double agent who controlled multiple intelligence networks. Behind the murder, there was a three-way secret war between the Japanese Special High School, the Kuomintang Renaissance Society and the underground intelligence network. As the investigation deepened, Shen Yan discovered that everyone at the banquet had been hijacked by Cao Huan in different ways, and all had motives for killing. The real murder method was a sophisticated ruse that used the banquet etiquette of the Republic of China to ensure that "only one person was killed." When the truth surfaced, Shen Yan faced a dilemma: arresting the murderer would detonate the North China intelligence gunpowder depot; letting the murderer go would mean burying the truth with his own hands. What decision will he make in the end?