The Tale of the Water Dragon

Set in a fictional world reminiscent of the early Second Industrial Revolution, Han Xuan, the illegitimate daughter of a noble family, and Su Qing, a journalist, are drawn by a twist of fate into a baffling murder case. As they investigate, they are horrified to discover that the case is tied to an exceptionally terrifying force.

P.S. Some elements are original creations. The heroine has a somewhat repressed personality, and the protagonists all have Chinese names, so it may feel a little jarring.