In the fourth episode, the students' outrage against Eddy's actions erupts, as they question his true intentions. The unexpected arrival of Pablo to join the student protest adds an extra layer of tension. The school is blocked, and teachers are left at a cafe, uncertain of what to do next.
Eddy receives a call from Lucie, informing him that someone from the school has contacted Sagirov. The message was sent from the same cafe, Chicken Street, which instantly casts suspicion on all teachers. Eddy assumes that Laurence, the Russian language teacher, is the mole.
Fabian, the security guard, sends Viviane a message about the escalating situation at school. However, a few brave students decide to break the blockade and enter the school to prepare for their exams. Eddy steps in to resolve the conflict and guides the students indoors.
Once inside the classroom, he urges the students to join the protest and forget about their exams. A short while later, he goes in search of Laurence and follows her to an alley where she collects a parcel. Throughout this, he remains connected with Lucie on the phone. Laurence spots and confronts him, but he plays along with her conspiracy theories and confirms that she isn't the mole.
Back at his home, Lucie tells him to search other teachers' lockers for clues. As they share a meal together, the conversation shifts to Lucie's husband. She eventually reveals that her sister used to work for one of Sagirov's associates. The sister became addicted to drugs but eventually went to rehab. Lucie's boss wanted to assign the case to someone else, but she is determined to bring Sagirov down.
Just then, a message from Sagirov's mole popped up, informing them of the Minister's upcoming visit. They turned on the news to find that the Education Minister would be visiting Eddy's school to investigate the issues and address the students' demands. Eddy could be discovered if he got on camera, so Lucie told him to stay away from the Minister and the cameras.
The next day, Tiphaine went to welcome the Education Minister. The minister gave textbook answers to all questions and prepared to leave as the students stopped her. When the students mentioned that substitute teachers were bad, she corrected them. But when it was revealed that Eddy, the substitute teacher, had put Benjamin on the mine, she asked to meet him.
Tiphaine went to bring Eddy and found him going through the teachers' lockers. He spit in Florian's water bottle and found a burner phone. Tiphaine caught him, but Eddy lied to get out of it again. He refused to go meet the Minister, and Tiphaine broke down.
She rambled about the frustrations of the job and life. Eddy consoled her, explaining that he wasn't going on camera because he had been to jail, which could reflect badly on her and the school. But he eventually gave in to her request. He went outside wearing a fish head mask, covering his entire face. The students cheered him on as he spoke to the Minister about the problems of the schooling system.
Amid the heated back and forth, the Minister revealed that her daughters went to a private school as she was aware of the problems in the government schooling system. Her statement put her career in jeopardy and exposed her hypocrisy as well. Eddy's act went viral all over the news, and he began to gain support for the issues he raised.
Back at his apartment, Lucie and he discussed the protest staged by several schools in Lille. She informed him that she would join him in his quest to catch the mole, whom we now suspected to be Florian. They engaged in a brief argument, and she blurted out that her husband had forbidden her from returning home until the investigation was solved.
The next day, the teachers and students took to the streets to protest. The policemen formed a barricade. Eddy proposed a strategy to take the students in the front and asked Florian to get in the back, whispering Sagirov's name to him. This spooked Florian, who fled. Eddy also discovered that the child was Sagirov's daughter, not a son. Theo intervened to help with a matter, and Lucie pursued Florian, engaging in a fight that she ultimately overpowered.
Simultaneously, Eddy donned the fish mask once again as he confronted the police barricade. The students provoked the policemen, leading to a scuffle. The episode concluded as the police took Eddy away for hitting one of them. He called out for Lucie as he was dragged away.
