Miracle doctor Shen Xici (the heroine) traveled to the world of immortals and became a low-level maid in the palace who was poisoned and in danger. In order to survive, she wore the skin of "gentle and weak" and gracefully slapped her face in palace battles, while secretly accumulating power. During this period, she rescued Ye Yan (the male protagonist), a young man who was being trained as a dead assassin.
The female protagonist regards the male protagonist as the most useful "knife", and she pretends to be gentle towards him but is actually taking advantage of him; the male protagonist regards the female protagonist as the only light in the darkness, and is actually extremely possessive of her when she is humble and thirsty for her.
