Eighteen years ago, seven housing estate teenagers including Lam Long-sang (played by Tan Jun-yin), Shen Jing-yat (played by Chan Shan-chung), and Xie Jiafu (played by Ho Yuen-tung) had a conflict with the gangster Wu Qi-si (played by Lam Ho-man), and Qi-si eventually fell to the ground... The seven people had a rift with each other and went their separate ways from then on. Eighteen years later, during the police investigation of a traffic accident, the skeleton of Qi-si was discovered. The seven sons could no longer escape the heinous disaster they had committed in the past! While struggling with contradictions, Long-sang and Inspector Yuen Lai-kin (played by Mandy Wong) of the Serious Crime Unit who was in charge of investigating the skeleton case developed feelings, and his heart became even more confused. At the same time, Lai-kin's father Ruan Jin (played by Lam Ka-wah) also secretly investigated the incident, which seemed to be related to the skeleton. As the truth gradually emerged, the seven sons were in danger. Who is the real murderer?