Thirteen years ago, Gu Yan of Dali Temple died in prison on the charge of "suicide out of fear of crime." Thirteen years later, his son Gu Changyan entered Dali Temple with the same official position. In the first month of taking office, he took on three cases: an official who was poisoned at the inn, a drowned man whose shoes were changed, and a corpse that was burned beyond recognition. Every one was like an accident, every one was too precise. The same dark blue thread appeared in all three scenes, pointing in the same direction - the "underground ditch" under the palace wall. People in Yongjing said: People in the canal cannot be touched. Gu Changyan didn't believe it. He has no background, no backing, and only one way: to tear apart the accident and dig out the people in the ditch one by one. The knife is not unsheathed. When you take it out of its sheath, you will see blood.
