We've seen and enjoyed the first two, so we were happy to watch the third: Detective Dee: The Four Heavenly Kings (2018). We have a new actor playing Detective Dee, Mark Chao, but Carina Lau is still Empress (Regent) and Hark Tsui is still directing.
This is a sequel to DD1, and prequel to DD2. It starts with the Emperor bestowing the Dragon Taming Mace, a legendary weapon, on Dee, and lets him know he can use it even against the imperial family, if necessary. Since empress Lau wants to be the ultimate power in China, this threatens her. So she enlists Feng Shaofeng, head of the palace guard to steal it back. He is Dee's friend, but loyal to the empire, so he agrees as long as Dee isn't hurt.
Meanwhile, she is gathering an army of sorcerers, who promise her the power she craves. She tasks them with getting the mace and killing Dee. He has gone into hiding and hidden the mace. At one point, the sorcerers are demonstrating their powers, and a dragon sculpture comes to life and starts killing people in clouds of smoke. Dee shows up in disguise and settles things, and figures out that this magic is based on illusion and mind control.
His research turns up an ancient Indian cult with mind control powers (possibly drug assisted). and sets out to fight them.
The whole science vs. magic and illusion is the basic theme of the Detective Dee stories, and it's fun to watch. This movie does the magic well, with the CGI improving in each movie. We get more of Dee's Investigation Bureau - a steadfast, strong and loyal crew, but maybe not as bright as Dee. The sorcerers are great villains, with grotesque costumes and weird powers. And in the end, when they are defeated, the Empress is freed from their hold and dedicates herself to the Buddha Guanyin. In fact, she's beginning to think she might be Guanyin herself, setting up the first movie.
My only complaints: It is rather annoying that the third movie has "four" in the title - especially because the Heavenly Kings in the title aren't really in the movie. And it doesn't look like Hark Tsui is making any more of these. If he does, I'll watch them.