Three years ago, police officer Liu Yuanwen sends back wrong intelligence, seemingly causing the death of his fiancée and fellow police officer Rong Yu. He also loses a friend in Rong Yao , his brother-in-law-to-be and member of the drug task force. Disheartened by all the events, Liu Yuanwen resigns from his position and cuts off all contact.
In the present time, Rong Yao has been promoted to leader of the task force, and is ordered to provide ongoing support and resources to the sole undercover operative in Group K, a drug cartel led by the ‘Spectre’ Mr. Ou. Turns out the undercover Mu Qing is actually Liu Yuanwen, and the pair must work together to bring the criminals to justice.
A story that follows undercover cop Gan Tianlei who spent 10 years of his life walking a gray area. After waking up from a serious injury, he restarts his life and tries to solve a case by relying on his lost memories.
Gan Tianlei, Yang Xiaolei and Xiong Guoliang used to be the solid trio of the police academy. However, Gan Tianlei was dismissed after he wounded someone in order to help Yang Xiaolei. After leaving the academy, he moves south to make a living and was recruited by Che Lizi of the Caesar Group.
Gan Tianlei encounters undercover police Uncle Hai and due to his influence, Gan Tianlei begins working as an informant for Tai Yongfeng. He eventually receives a special appointment to become a policeman in order to bring down Caesar Group. Before they could succeed, Gan Tianlei gets caught in an explosion and falls into a coma. Eight years later, Gan Tianlei awakes in the hospital with no memories. The case against Caesar Group has been dismissed due to lack of evidence and Gan Tianlei's memory may be the only key.
