Underwater killers Su Muyu and Su Changhe have formed a life-long bond since they were in the Purgatory of the Unknown One.
The life-saving herbs Hantan handed over when he was about to die, and the warm blood that entered his throat in the poisonous fog forest, made them the only anchor point for each other in the dark river world where everyone ate each other.
After becoming official killers, the two teamed up to travel all over the world: stabbing in Tianqi City at night, and when the umbrella blade spun down, he always knew that the knife would be behind him; in a ruined temple, warming himself by the fire on a cold night, and when his fingertips accidentally touched, his heartbeat shattered sparks.
Su Changhe's crazy possessiveness broke through Su Muyu's secret desire that he had held back for many years - from the taboo suggestion of "borrowing his own body to express his feelings" to the sinking of the blade and umbrella. In the gap between blood and darkness, they gnawed out the salvation that belonged to each other, and also grasped the true feelings that they dared not express in their mouths.
Purpose: Find the only salvation in the murder of the dark river, intertwining forbidden true feelings with the blade and umbrella