On the bank of Tonghe River in Haizhou City, new clues to the "8.17 case" five years ago surfaced. Zhou Jin, an investigator from the Nancheng Public Security Bureau, volunteered to join the investigation because her brother Zhou Chuan was one of the two special police officers who unfortunately died on duty in the case. With the help of criminal psychology professor Jiang Han Sheng, the police locked in a criminal group headed by the mysterious man "Lao Xie". At the same time, Jiang Cheng, the undercover policeman who has been carrying out "Operation Hidden Front" for five years, has also penetrated into the core of the enemy and is only one step away from the "Old Scorpion". In order to wipe out the criminal syndicates, three young people, Zhou Jin, Jiang Han Sheng, and Jiang Cheng, who grew up together in Gardenia Lane, tried their best in their respective positions, fought wits and courage with the criminals, and defeated evil with justice, courage and wisdom. (Source: Chinese = Weibo || Translation = MyDramaList) ~~ Adapted from the novel "Gang Tie Sen Lin" (钢铁森林)by Qi Wu Guo (弃吴钩).