Since Xia Di (Xing Zhao Lin) lost his friend in an accident when they were climbing a mountain five years ago, the once confident and carefree young man has turned cautious and listless. But when he meets university student Lin Feng (Eleanor Lee), who dresses like a man and teaches mountain rock climbing, his heart slowly starts to melt.
Fifteen years ago, a female child was kidnapped on the way from school. At that time, Piao Hai Ying (Wang Tian Chen), who was an elementary school student, witnessed the girl being taken away. A few days later, the girl was found dead, and detectives couldn’t find the culprit. As time went by, Hai Ying started distrusting the police. Fifteen years later, Hai Ying is now a police officer and criminal profiler. One day, he finds a walkie-talkie that allows him to get in contact with Detective Li Cai Han (Du Chun) who is in the past. Police officers Hai Ying, Cai Han and Che Xiu Xian (Li Xiao Ran) then set out on a journey to solve cold cases.
The relationship between the rebelling Qi Qi (Mi Mi) and her foster father Lin Huan Zhi (Andrew Lien) is very tense. Qi Qi who is suffering from depression turns to the internet where she gets to know Bao Bao Lan (Alana Yang) and You Nuo (Lin Huan Zhi). Although all very different in character, the three girls come to trust and appreciate each other. Meanwhile, band leader and main vocalist Lin Nan Yi (Eric Zhou) also appears in Qi Qi’s life.
Hao Yun (Michael Chen), a vet at a private clinic, leads a mundane life until he accidentally discovers the world is inhabited by monsters. Worried about the secret of their existence leaking, monsters capture Hao Yun and attempt to erase his memories. When their attempts fail, Hao Yun is forced to join Monsters Bureau, where he solves cases involving monsters with the help of his new partner, Wu Aiai (Wang Zi Wen). As Hao Yun dives deeper into this new world, he learns that even monsters must deal with the mundane struggles of everyday life and the entanglements created by human emotion.