Mr. Bo's Black Moonlight

Forgive me for my lack of IQ. After reading five chapters, I didn't understand the background era of this book. The character settings are a bit ridiculous. Before the heroine traveled through time, she drank poisoned medicine for six years? I don't understand. Anyway, I am a layman. Apart from my mother and father, I have never taken medicine given by others... Of course this is not important? As a female spy, the first thing she does after waking up is to return to her original owner's home? What's the meaning? What's the purpose? All in all, this is not criticism for the sake of criticism. When I read this book, I had the same feeling: I am confused...