The perfect crime. One fine morning, math teacher Zhang Dongsheng pushes his rich relatives off the observation deck of Sanminshan National Park. Everything is calculated to the smallest detail.
The police considered it an accident.
Close people. Zhu Chaoyang is the best student of the school. Because of his thirst for knowledge, Zhu is endlessly lonely. Everything changes when his childhood friend Ding Hao unexpectedly returns to his life with his named sister Pupu.
They escaped from a shelter for children whose parents were convicted of murder, and now they are in desperate need of money.
Blackmail. While walking in the park, the teenagers accidentally filmed Zhang's murder on camera. And now they are offering the killer to buy back dirt, ready to do anything to achieve their goal. But Zhang also has no intention of dancing to someone else's tune. And then the darkness begins...