A story that follows three children from a coastal town who unintentionally film a murder scene. As the kids become involved with the suspect, it opens up a case that is far more complicated than it looks and entraps several families into an unpredictable outcome.
In the summer of 2005, a meeting takes place at the middle school of a small seaside town ahead of summer vacation.
Zhang Dongsheng looks guilty as he is questioned by the police. The three kids decide to remind the murderer about what they know, and send a warning letter.
Zhu Chaoyang takes advantage of Zhang Dongsheng's carelessness and plants the warning letter; Zhu Jingjing convinces Pu Pu to stop bullying her.
Zhang Dongsheng confirms that the children have video evidence of the crime after following the trail of the warning letter.
Wang Yao visits Zhu Chaoyang's home, and Zhu flees in fear that he knows he was responsible for the death of his daughter.
Wang Yao is desperate to find out the truth, and will stop at nothing; Yan Liang goes to the secret meeting place and finds Lao Chen waiting for her.
Father Zhu starts swimming with Chaoyang to make up for his lost father and son time; Zhu Chaoyang goes to Zhang Dongsheng's home to negotiate terms of peace.
As the crime continues to ravage the town, the children grow more and more impatient with the suspects and take matters into their own hands.
Wang Yao's younger brother takes Zhu Chaoyang to the fishery to torture him for information; Zhang Dongsheng fights with Wang Li as he asks for money.
Zhu Ma asks the police about Zhu Chaoyang's situation, and she discovers she's been lying; Zhang Dongsheng feels betrayed by Yan Liang yet again.
Zhang Dongsheng, Yan Liang, and Zhu Chaoyang make a lucrative deal; Wang Yao and Zhu Yongping stumble into an unfortunate situation and violence ensues.
Yan Liang and Zhu Chaoyang finally decide to take down Dong Sheng; Zhu Chaoyang tells the police what he knows and starts from the beginning.
