The male protagonist Ji Bai (played by Wang Kai) and the female protagonist Xu Xu (played by Wang Ziwen) are a master and apprentice who seem to have a cold relationship, but they are actually comrades-in-arms who depend on each other for life and death, and they are also lovers who admire each other. Ji Bai is a deep and cold senior detective, and Xu Xu is a talented newcomer in criminal psychology research. After the two jointly solved a major case, Ji Bai fell in love with this simple and wise apprentice, but no matter how he pursued her openly or secretly, this girl who was as slow as a "snail" just couldn't receive the signal of love. When the two "talked about love and the case", it was also an extremely sweet but also extremely dangerous journey of chasing the murderer.