TimSir (played by Ouyang Zhenhua), a senior chemist of the Ministry of Justice, is knowledgeable and has repeatedly solved strange cases with his superb evidence inspection techniques. His subordinate and friend, Sam (played by Lin Wenlong), is also an excellent forensic doctor. Recently, he is preparing to marry his girlfriend Tingting (played by Zhong Jiaxin), who has been in love for many years. Sam's friend Ivan (played by Zheng Jiaying) has just returned from the UK. He safely detonated a bomb during a bomb crisis, which made TimSir look at him differently. At this time, Senior Inspector Ma Guoying (played by Charmaine Sheh) of the Anti-Drug Unit and a group of men are tracking down Hong Kong's drug lord Dai Gui. Dai Gui forced another drug lord in Hong Kong, Shi Tou Yong, to dominate the entire Hong Kong market. Just as the Anti-Drug Unit and the Forensic Team worked together to track down Dai Gui's men and foreign drug dealers, and were ready to arrest the triumphant Dai Gui, the car Dai Gui was riding in actually exploded. It happened that at this time, Tingting and TimSir's girlfriend, Senior Inspector Xiaorou (played by Meng Jiahui) of the Serious Crime Unit, passed by. The explosion killed Tingting and seriously injured Xiaorou. Sam, who was preparing to get married, was heartbroken after hearing the news. Guoying was transferred to the Serious Crime Unit. She suspected that Dai Gui's explosion was caused by Shitou Yong's revenge, so she began to investigate. Just when the case was at a stalemate, Sam seemed to get a hint from Tingting and finally found evidence that Shitou Yong had committed the crime...