Qin Feng thought he was going to attend his distant uncle Tang Ren's wedding, which turned out to be a hoax. Tang Ren had deceived Qin Feng to come to New York for another purpose. Godfather of Chinatown, Uncle Qi, gathered the world's best detectives from an app called Crimaster and set up a competition to locate his grandson's killer within one week for a reward of five million dollars. His grandson Jason was found in a temple with his heart torn out and an unknown symbol on a table near him. Unexpectedly, Qin Feng, the world's second-top detective and the world's third-top detective noticed another similar murder in the Hudson River one week before the investigation began. A white woman was also killed but lost her kidney. The two men pulled out surveillance videos of the two crime scenes and found that a man appeared at both crime scenes. They identify the man as Song Yi. However, after observing that Song Yi is right-handed, Qin Feng concludes that he could not be the killer since evidence suggests that the killer is left-handed. While Qin Feng and Tang Ren knew that Song Yi was not the killer, this was not everyone else's consensus, and so the duo had to clear Song Yi's name and find the real killer. Eventually, with the help of Tang Ren's knowledge of Feng shui and Wu Xing, Qin Feng discovered the killer's motive. Due to the unique location of the murders, the time of the crimes, the eight characters of the victims' birthdays and the organs, he concluded the whole of New York was being used as an altar. Finally, they find out that the doctor who was battling cancer believed that doing ancient Taoist rituals could grant him immortality, and was behind the murders. The doctor kills himself after being found out. Qin Feng deduces that Song Yi is actually the mysterious man "Q", the top-ranked detective of Crimaster. Song Yi solved the case very early on and used the doctor's patterns to cover up his own murder of a sex trafficking ringleader who abducted his sister. Qin Feng lets him go, but later KIKO reveals that "Q"'s IP address does not locate him in America, making Song Yi as "Q" unlikely. "Q" is therefore still at large.
Detective Chinatown 2 earned $541.1 million in China, and $3 million in other countries, for a worldwide total of $544.1 million.
Critical response
On review aggregator website Rotten Tomatoes, the film has an approval rating of 54% based on 13 reviews, and an average rating of 5.1/10. On Metacritic, which assigns a normalized rating, the film has a weighted average score of 52 out of 100, based on 4 critics, indicating "mixed or average reviews". Chinese Douban gave the film a user rating of 6.7/10. Tianjin Maoyan Culture Media gave the film a 9.0 rating based on 23 million ratings.
