Out of heartache, Qiao Ling's friend Xu Shanshan turns to the three of them to win back the love of her life. An assignment that is supposed to be simple gets out of hand when Cheng Xiaoshi is suddenly drawn into a criminal case. 

Cheng Xiaoshi and Lu Guang continue to search for Xu Shanshan and are suddenly confronted with a serial killer. For their safety, they must make a dangerous pact with the killer.