Qiao Xiquan, a timid girl in high school, was forced to live in her aunt's house after her father disappeared for no reason. The aunt suffers from mild schizophrenia, the uncle is addicted to alcohol and lust, and their only daughter Lin Xiaoguai is also violent and unpredictable. Qiao Xiquan's biggest wish is to find out where his father is and escape from this terrible nightmare before summer arrives. Unexpectedly, classmate Xing Twelve was accidentally killed, but Qiao Xiquan was involved in an endless dispute for no reason. This dispute brought huge disaster to Qiao Xiquan.
Out of responsibility and guilt, the young class teacher Shangguan Yixun persisted in finding the real culprit who killed Xing Twelve after the police concluded the case as suicide; Xu Che was Qiao Xiquan's classmate. Because of the beautiful feelings he had during adolescence, he did not want to see the girl he liked hurt, so he secretly joined the search for the cause of Xing Twelve's death. However, behind the truth, there are blood-soaked secrets one after another unknown to the public. These secrets involve the mystery of Qiao Xiquan's father's disappearance, Shangguan Yi's true purpose of investigating the case, and the causes of his aunt's schizophrenia... When the truth is revealed and the dark side of human nature is made public, no one can return to their original life track with peace of mind, and they fall into the abyss of sin again.