Basically the premise is, "imagine that the first Emperor of the Ming dynasty was actually a woman" and go from there. In saying that it skips over a lot of the possible issues that come with a woman pretending to be a man and more focuses on the "attempting to become Emperor" bit.
I really enjoyed how the main character, Zhu, wasn't shy or quiet like someone you would expect to be who is hiding their gender to be. They're talkative, witty, and willing to do whatever it takes to get to the top. This lack of a moral compass towards the end kind of sucks, but I guess that's what it takes to become Emperor.