In year 2006, female university student Yin Lu met with a mishap. Due to lack of clues, the case is left unsolved. Lian Zhou who is Yin Lu's boyfriend, went to Gu Cheng the last place Yin Lu might be at, to find out the truth despite everyone's objections. He tried to investigate thoroughly taking the cover of a gas tank delivery man.

Strange crimes occur in Thailand as the ranking for the world's best detective sees a shift. New detectives come into the picture to tackle three difficult cases.

Police officer Bao Yu is working undercover as drug dealer Jin Fei's subordinate and is eventually able to work directly under powerful drug lord Tian Jing after befriending his daughter, Tang Guo. However, Bao Yu is not fighting the drug cartel alone - he also has a support network including fellow undercover colleague and romantic interest Guan Xiao Zhi, police chief Fang Qing Long and anti-narcotics team leader Lian Zhong.

In 2003, a small mining town in Ningxia faces relocation when a burned body appears, echoing an unsolved case from a decade earlier. Veteran detective Chu Zhiqiang teams up with Zhang Tao, a reassigned investigator, to uncover the truth as the town prepares for relocation.