In 1919, with the end of the First World War, war-torn Europe had not yet recovered. The Paris Peace Conference, which aimed to solve the problems left over from the war and lay the foundation for peace, was about to be held. As one of the victorious countries, China sent a delegation of five people, including Gu Weijun (played by Chen Daoming), then the ambassador to the United States and the plenipotentiary, to participate in the conference. However, in the context of the desire of European and American countries and Japan and other powers to redivide their spheres of influence, the number of Chinese delegations was reduced, and Germany's interests in Shandong were about to fall into the hands of Japan. Gu Weijun made an impassioned speech at the meeting, refuting the unreasonable demands of the Japanese side, but justice seemed so fragile in the face of interests. Mei (played by Xu Qing), the wife of Gu Weijun's friend Xiao Kejian (played by He Zhengjun), made a special trip to Paris to find Kejian who had joined the patriotic workers' movement. Kejian's activities in France and the huge public voices in the country made Gu Weijun and others in the conference feel a great responsibility.