Shi and Wang encounter a murder investigation on their train journey to Hailar, realizing Shen is targeted by another formidable force. Ye advises Shen's safety while sharing her past with Wang.

Wang and Shi regroup, sharing findings and returning to Beijing. Xu continues Shen's investigation. Ye confronts ETO leader Evans, revealing ideological divides. Wei seeks solace in mathematics amidst threats.

Police find Shen's death a suicide, clearing Pan. Wang attends a Three-Body game meetup where Pan reveals extraterrestrial existence. Meanwhile, global preparation against the aliens begins as mistrust spreads.

Ye's interrogation of former Red Guards yields no remorse. Wang joins her team. Ye meets Evans, who, disillusioned with humanity, builds "Judgment Day," inheriting wealth but not his father's business.

Shi proposes using Wang's flying blade to slice Judgment Day, aiming to secure Trisolarian data.