My thought process for ordering Black Dragon (which originally went by the title Miracles) was something along the lines of, "OK, it's a period piece romance set in 1930s Hong Kong, starring Jackie Chan - who is looking quite dapper on the box art - and Anita Mui, who was outstanding in Legend of Drunken Master. Yeah, I'll try that.'
The film didn't quite end up being what I expected. Chan's this country rube Cheng Wah Kuo, who comes to the big city, and through a series of events centering on his buying a rose from an older lady selling flowers (called Madame Rose), he finds himself the head of a criminal syndicate. Cheng doesn't want any part of criminal enterprises, so he tries to redirect the organization to running a nightclub, and a singer named Luming (Mui) just so happens to show up looking to repay the debt her late father owed to Cheng's predecessor.
As it turns out, we don't see much of the romance between Luming and Cheng. The majority of the story is taken up with Madame Rose's troubles. Her daughter is coming to visit with her prospective fiance and his wealthy father, and Rose has been telling her for years about how she and Belle's stepdad are doing well, they're wealthy aristocrats. So Cheng gets roped into helping put on an elaborate hoax to help Madame Rose appear to be what she said. While he has traitors in his midst, and a rival crime boss trying to take over. The plotline between Cheng and Luming is largely nonexistent, beyond her yelling at him for always listening to "Uncle Hai", who was the chief adviser to Cheng's predecessor. That basically boils down to her wanting him to make his own decisions (which will match with her wishes, naturally).
There's a decent idea in there about Cheng trying to do the right thing, help people, while also making some decent scratch for himself, but it kind of gets lost among all the other stuff. Mostly it gets buried under the "fool the in-laws to be" stuff. If you aren't really interested in that (and I wasn't particularly), it can be a slog. Waiting for the next meeting with Tiger, or the occasional fight scene, or even the arrival of Inspector Ho. He's the high point of the false identity thing, because he wants to butter up the father-in-law, but Cheng foists the con man they hired to play Madame Rose's husband on him, and that guy fleeces Ho. I'd feel worse for him if he wasn't such a lousy boss, and a lazy cop to boot.