I am gonna rate it 10 now, and bet, that after the series finishes airing, I am not gonna change this rating.

I would say "watch this drama for its male lead", but actually there are many, many reasons to watch this drama, so let's just start with the MALE LEAD.
This is a proof that male lead in Chinese historical drama can be not stone-faced and cold, and still radiate enormous quantity of testosterone. He is hot, strong, smart, seductive as a devil, but he doesn't hide his feelings. He is not the nicest person at first, his job demands him to be tough, but even in the first episodes you can see he has a good sense of humor. Later you will laugh like hell while watching his comic scenes with the FL. Moreover, this amazing man talks with his real voice here, and it's sooo sexy.

GOOD PACING. Drama has very good pacing and is plot driven. Characters seem to be in constant movement, one case/trouble follows another, all interactions are dynamic, sad scenes are sometimes followed by funny ones, so some episodes are a roller-coaster of emotions.

SMART FEMALE LEAD. Many dramas declare having a smart female lead, but very few manage to actually make her equal to the male lead. Here they are equally smart, he is just a bit more experienced. She escapes many troubles alone, and there is no feeling, that whatever bad is happening to FL, suddenly ML will just fall from the sky and save her. But sometimes he comes and saves, yes ;)
Some viewers called FL selfish, and it's true she cares about her own wellbeing and is not ready to sacrifice herself for the sake of the family, especially when it's her family which threw her under the train. Later on FL's relationships with her family will have a nice development, and at certain point you won't be able to call her selfish anymore.

VERY GOOD SCRIPT. Investigations are quite good, full of twists, and many of them you would never see coming. Dialogues are brilliant, and not once you will notice how creators were getting close to the trap of one or another cliche and then just avoided it with a stylish maneuver. Many times I noticed that a typical scene, which I saw many times in other dramas, here developed totally different, yet still exciting. Some misunderstandings which for sure would happen in other dramas in similar situation - here never happened.

Need more reasons? AMAZING CHEMISTRY between the main leads. All their scenes are exciting and give you butterflies, even though this is a slow burn and it will take them time to fall in love and then to confess, but for me this is one of the most believable romance developments I've seen. They even don't like each other at first and it's also believable, I would call it a rational prejudice. Although they are wrong about each other, they still talk and act very honest, and it takes a few episodes to bring their relationships to another level. Unlike other dramas with enemies-to-lovers scheme, where leads pretend to have another personality and hide their true motives and feelings, here leads always stay true to their personalities, and never act weird just to annoy another person.
Oh, btw, it does remind "Pride & Prejudice" a bit.

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Important warning: non graphic r**pe happens in episode 19 to one of the ladies of FL's family.

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The things that might scare you in the beginning:
- FL's huge family - you are gonna hate them at first, but just give them time, some of them will die, the rest will redeem themselves a bit.
- Not always perfect delivery of lines. Actors speak their own voices here, which is a rare thing, so production might have faced some troubles, but let's support them, I want to hear real voices more often! Also, we are so lucky to hear ML's fantastic voice.
- FL is manipulative, especially towards SML - that's true, at least in the beginning, but please try to understand what she was going through in those first episodes.
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So, GO AND WATCH NOW and suffer with us, while waiting for next episodes to air.