Episode 4 recap: Fang Li defected to Unit 76.

Zhou Shao Zu deliberately provoked Shen Qiuping and ended up kidnapping her when she got close to him. He knew that Chen Ke Hai intended to capture him alive without using a gun. However, during the negotiation between them, an unknown assailant killed Zhou Shao Zu from behind. Their plan failed, and although Chen Ke Hai looked around, he couldn't identify the shooter.

At that moment, Fang Li arrived and escaped with Shen Qiuping. Chen Ke Hai dragged Zhou Shao Zu's body into the house, pretending to ask questions and lure out the mastermind behind the scenes. Suddenly, a man sneaked into the room, and to Chen Ke Hai's surprise, it was Instructor Miao, who knocked him out.

When Chen Ke Hai regained consciousness, he found himself tied up in an interrogation room. He knew that Instructor Miao wasn't the mole, but Instructor Miao shifted the blame onto Fang Li, transferring the suspicion onto him. In order to protect Fang Li, Chen Ke Hai confessed to being the mole. However, he proposed a suggestion if they truly wanted a scapegoat. Instructor Miao, impressed by Chen Ke Hai's intelligence, assigned him a special mission.

Fang Li reported to Instructor Miao and explained that Chen Ke Hai was not the mole. Meanwhile, Director Dai gave Fang Li a separate task. Chen Ke Hai was officially declared as the mole and publicly sentenced to execution. Li Tang's successful completion of the mission helped clear his name, and the entire group of trainees graduated early. Their first assignment after graduation was to assassinate the mayor of the Wang puppet government, Zhou Bing De. Instructor Yao explained the assassination route.

Fang Li's mind was preoccupied with Chen Ke Hai's execution, and Instructor Miao brought his thoughts back on track. Fang Li was chosen because he showed the determination to achieve his goals by any means necessary. Near the entrance of the interrogation room, Fang Li pulled Shen Qiuping back and informed her that he couldn't orchestrate an escape from the prison. He deliberately hugged Shen Qiuping and revealed their escape plan in front of the guards, staging a romantic scene. Qiao San stole the keys from the guard, and during a meal delivery, Fang Li conveyed the escape plan to Chen Ke Hai.

The trainees began their operation to assassinate Zhou Bing De. During Chen Ke Hai's guard duty, he managed to escape and overheard a conversation among the drivers of the transportation team. He learned that the two vehicles would depart one hour later to avoid an ambush. Based on this information, he suspected that there was a problem with Fang Li's mission and quietly boarded another vehicle. Instructor Miao and the other instructors were on their way back when they discovered that the female instructor was the real mole. She had investigated the whereabouts of Zhen Zhen, who graduated early, and during the operation to capture Zhou Shao Zu, she secretly transmitted information to the butler and canceled the transaction. It was also her who killed Zhou Shao Zu. Instructor Miao confirmed her identity as the mole through a secret telegram and discovered that she was actually a Japanese national.

Yang Zhen Zhen obtained the schedule of Zhou Bing De's theater visit and deliberately had the trainees ambush him on the road. Zhen Zhen and Zhou Bing De's driver went out, and her identity was exposed. She was directly killed by Xing Han Zhu, the head of Unit 76. Xing Han Zhu then boarded a vehicle and asked Li Shi Qun if the information he received was accurate. Were these really a group of new trainees coming to assassinate Zhou Bing De? They wanted to catch them off guard. Instructor Miao observed everything from across the theater. Fang Li, Shen Qiu Ping, and others were already lying in wait outside the theater. At that moment, Chen Ke Hai took a risk and notified them that there was a problem with the mission. Chen Ke Hai asked Fang Li to leave as soon as possible. Just then, Instructor Jin emerged from the theater, and Fang Li used a gun to force Chen Ke Hai to leave. Zhou Bing De's convoy arrived, and Li Tang and others began their ambush. Chen Ke Hai and Shen Qiu Ping also entered the battlefield. Fang Li opened Zhou Bing De's car and discovered a hidden bomb inside. Instantly, the casualties among the trainees were severe. Despite the danger, Chen Ke Hai fought alongside Shen Qiu Ping, driven by their camaraderie. However, they were outnumbered, and both Fang Li, Shen Qiu Ping, and Chen Ke Hai were shot and fell to the ground. The trainees suffered heavy casualties.

After Fang Li regained consciousness, he led a group of surviving trainees to defect to Unit 76. With his ruthless tactics, he quickly rose through the ranks and became the head of Unit 76. In the blink of an eye, communist underground comrades arrived in Shanghai with intelligence. They appeared as his wife to assist him, but they were arrested while exchanging information covertly. The female communist died on the spot, and the male communist was captured and brought back to Unit 76 by Li Tang. Xing Han Zhu complained to Li Shi Qun about Fang Li overshadowing him and crossing into his jurisdiction to make arrests. He felt that Fang Li was seeking personal revenge, especially since two years ago, Fang Li's classmates died at his hands. If it weren't for the dozens of lives at the Jiangsu Bank, how could Fang Li be on equal footing with him? Li Shi Qun comforted him, regarding Fang Li as a dog. He explained that the reason Fang Li was given such a high position was to make him sacrifice himself.