The Perfect Crime. One fine morning, math teacher Zhang Dongsheng pushes his wealthy relatives off the observation deck of Sanminshan National Park. Everything is calculated to the last detail. The police deemed it an accident.

Close people. Zhu Chaoyang is the best student in the school. Because of his hunger for knowledge, Zhu is endlessly lonely. Everything changes when his childhood friend Ding Hao and his baby sister Pupu unexpectedly return to his life. They have escaped from an orphanage for children whose parents are convicted of murder and are now desperate for money.

Blackmail. While walking in the park, the teens accidentally caught Zhang's murder on camera. And now they offer the murderer to buy the dirt, ready to do anything to achieve their goal. But Zhang has no intention of playing along. And then the darkness begins...