After the events in Bangkok and New York, Tang Ren and Qin Feng are invited to Tokyo to investigate another crime that has occurred there by Noda Hiroshi regarding a murder of a Southeast Asian gang boss, Su Chaiwat, leading to a battle between the strongest detectives in Asia.
However, as they were leaving, they were stalked by Thailand's newest great detective, Jack Jaa who has been steadily climbing the Crimaster app into the top ten rankings and working on the Southeast Asian gang's side to figure out how their boss died.
After a tussle with Tang and Noda, Jack decided to put their differences aside and work temporarily with the trio as they were on the same boat of investigating the same case.
With Qin being incarcerated for the murder, Tang was sent back to Thailand on a boat to "lay low" and John had travelled to Suihua, Heilongjiang, China with both parties having left the country to gather better evidences and guidance on the case.
Meanwhile back in Thailand, Snow met with Tang and after showing the discrepancy between how the kidnapper had died versus how low of a probability of Qin pushing him to his death, Tang returned back to Japan and the crime scene to run tests with the assistance of Kiko infront of the prosecutor of Qin's case.
Noda then appeared and revealed that prior to the four detectives even entertaining the games, he had sprayed a sort of invisible ink over the money and with Qin having a hand in handling them, his hand would have stained the kidnapper if he had pushed him to his death but the kidnapper had none of the ink blots on his corpse thus ruling out that Qin had actually pushed him to his death.
With the help of Kiko, they restructured the entire glass panel and declared that one piece of the shrapnel was missing from the scene and it was the final murder weapon used to assassinate Chaiwit.
[6] Warner Bros. Pictures planned to distribute the film in select theaters in the United States on January 24, 2020,[7] but the release was postponed likely for the same reasons as the initial delay in China.
[15] Todd McCarthy of Deadline Hollywood was less favorable, writing: "Its enormous box office numbers notwithstanding, I have to rate Detective Chinatown 3 as something of a disappointment after the raucously engaging first two entries.
"[16] John Berra of Screen International gave the film a favorable review, writing that it "exudes a heightened zaniness which is most welcome in today's largely homogenised franchise landscape" and "is an insanely colourful, no expense spared blockbuster".
Prior to the original release date during the Chinese New Year season of 2020, a web series that follows the events after the first Detective Chinatown film premiered on January 1, 2020.
This series introduces three new detectives: Lin Mo (Roy Chiu), Sa Sha (Zhang Yishang), and Noda Koji (Chen Zheyuan).
The film Detective Chinatown 1900 serves as a prequel to the series, set during the Qing Dynasty in city of San Francisco, California.
The plot centers on a mysterious murder of a woman in Chinatown, San Francisco, with suspicion falling on a Chinese man, leading to public outrage and demands to shut down the neighborhood.
Amid this turmoil, Chinese medicine practitioner Qin Fu (Liu Haoran) and his companion Ah Gui (Wang Baoqiang) become entangled in the case.
As they navigate a tense, time-sensitive investigation, the duo engages in a battle of wits and courage to uncover the true culprit behind the crime.