A young man goes to great lengths to enter the drug syndicate to finish the undercover mission that his girlfriend started. Fang Han (Qin Junjie) and his girlfriend were childhood friends. She was an exceptional cop and undercover. Upon finding out that she was killed, Fang Han is overwhelmed with grief. He receives a secret code that only he can understand and accepts a mission to infiltrate the drug ring himself. Acting impulsively and always putting himself on the line of fire gets him noticed by their target Gu Tao (Xue Haowen) who begins to trust him. As they encounter countless dangers, Fang Han inches closer to finding his girlfriend's killer and to bringing down the syndicate once and for all.