《墨之城》（City of Ink），美国作家艾尔莎·哈特（Elsa Hart）著清朝推理小说系列第三本。 内容简介
Li Du was prepared to travel anywhere in the world except for one place: home. But to unravel the mystery that surrounds his mentor’s execution, that’s exactly where he must go.
Plunged into the painful memories and teeming streets of Beijing, Li Du obtains a humble clerkship that offers anonymity and access to the records he needs. He is beginning to make progress when his search for answers buried in the past is interrupted by murder in the present.
The wife of a local factory owner is found dead, along with a man who appears to have been her lover, and the most likely suspect is the husband. But what Li Du’s superiors at the North Borough Office are willing to accept as a crime of passion strikes Li Du as something more calculated. As past and present intertwine, Li Du’s investigations reveal that many of Beijing’s residents ― foreign and Chinese, artisan and official, scholar and soldier ― have secrets they would kill to protect.