Boy, what a letdown.
I don't mean to somehow suggest that Tsui Hark's martial arts fantasy-mystery Detective Dee and the Mystery of the Phantom Flame (2010; released in the US in 2011) was some kind of masterpiece; it wasn't. But the original Detective Dee movie had a coherent story, engaging characters, and cool fight scenes choreographed by Sammo Hung. In the new prequel, Young Detective Dee: Rise of the Sea Dragon, Andy Lau has been replaced as Detective Dee by Mark Chao. This makes sense at first, since this is supposed to be Dee's first case, set in the year 665, when Dee was about twenty-five years younger than the version we've seen. But, upon closer inspection, there's no real reason for this story to be Dee's first case, and one gets the suspicion that at some point Andy Lau was handed this script and responded, "What the hell do giant sea monsters have to do with the Tang Dynasty and Detective Dee?" And then Tsui Hark responded, "Fine. Screw it. We'll reboot the franchise!"
At first, Young Detective Dee looks like it is going to be a perfectly fun retread, giving us the same plot set-up with the elements tweaked a bit. Instead of people spontaneously combusting into flames, they are attacked by sea monsters (one enormous and one vaguely humanoid). Instead of teaming up with the Empress's top cop, Dee teams up with a prison doctor who knows a little bit about what consequences would lead to a human body changing into some kind of humanoid sea monster. Feng Shaofeng has essentially the same role played by Deng Chao in the first film: the detective trying to solve the same case who first considers Dee an enemy then reluctantly join forces with him. However, instead of Deng's albino-ish blond hair, Feng has dyed red hair.
Perfect! It's going to be the same but a little different... except then it isn't. At all.
While Detective Dee was shown to utilize some deductive reasoning in the 2010 film, Young Detective Dee is introduced as a full-on mix of Robert Downey, Jr.-style Sherlock Holmes and Rain Man. He can read lips. He can visualize an abduction before it takes place. He can deduce the prison doctor's elaborate back story after a brief glance at him. Of course, almost none of these skills pay off later, but who needs consistent characterization and plot-hole-free storytelling when we've got sea monsters?!
There's also a courtesan named Yin (Angelababy; no really, that's her stage name) who, at the beginning of the movie is going to be sacrificed to the big sea monster, but then turns out to be the long lost lover of the humanoid sea monster. Or something...
It's sort of hard to keep track of all this stuff. Look, the original Detective Dee movie was about two hours long, and probably could have lost 20 minutes of weird subplots in the middle. Young Detective Dee is over two hours long, and probably needs to be trimmed by about 45 minutes. I spent long stretches being either bored or confused.
The prolonged special effects sequences don't help either. Though Young Detective Dee is no doubt much higher budgeted than its predecessor, it is also much more elaborate and the resources have been spread thinner. Therefore, overall, it looks cheaper and cheesier. Add to this the fact that Young Detective Dee is supposed to be a 3D movie -- and not "the feeling of depth is interesting" 3D but "crap is flying at you constantly" 3D -- and this 2D version frequently ends up looking wrong.
The cast, including a returning Carina Lau as the Empress, is quite good. There's a funny section where they uncover a medical reason to make a thousand people drink a eunuch's urine. Also, there are two exciting action setpieces near the end of the movie: an elegantly choreographed fight on a sheer rock face and the final major battle with the giant sea monster. You know, all that would almost be enough to recommend the movie if anything in the story made a lick of sense from scene to scene.