The series is a gothic romance about a red head chick who is meant to kill the king of a neighboring country. That country (G) has 3 princes. All 3 that want to fuck the red head. Also their is death and other regular fucked up stuff in this series.
The red head is supposed to kill the king via poison. She is part of this country which trains women in the art of poison calling them poison princesses. It's messed up shit. Since birth they are given small doses of poison. Like in their milk. Or their bed sheets. To the point that when they are adult-ish They are basically a walking killing machine. The air they exhale is poisonous, their tears are poisonous and any body fluid that touches another person will kill them in a minute. Its fucked up stuff.
Now this all sounds awesome. And badass but its done so poorly. The series isn't even about assassination mission either Despite being the main plot point. The series is more about the 3 brothers with their own personal issues. The eldest being the crown prince. The middle child who is meant to taste test everything for the crown prince and the youngest who just fucks about but is also a mega genius obviously. Its more their story and she happens to be a caught up in it.
Honestly when this series stops being about the main heroine and more about the brothers in the later half is when this series got much better. Their is this political rivarly and assassinations against other people, a very tiny war arc and other historical bad ass moments. The romance felt incredibly flat. But it wasn't really the main focus anyway.
The first half kinda sucked though. Felt too edgy and they did this thing where you would see the same thing over and over again but in different points of view. So i read the same chapter for an entire volume and learned 10% more instead of the author creating just 1 chapter and explaining stuff properly. It also had the opposite in the very first volume where the author dumped tons and tons of exposition.
TLDR: 2nd half was better when they didn't focus on the princess. Overall it became much better. Was gonna give it a 6 despite the weak start but the ending was, cliche(?), or weak lets say. 5/10