The episode begins in a bustling nightclub where the crowd is immersed in the rhythm of dance. Our protagonist, Eddy, appears in disguise and encounters several individuals within the club. He converses with a man in a suit about investing a 60% advance in a Dubai scheme. Later, he meets a powerful boss behind the club's operations. Eddy hands over some gold coins to the man, who promptly verifies their authenticity.
The man attempts to deceive Eddy by offering him less money, but our hero outwits him by quoting the correct amount. As the situation escalates, the man reaches for his gun, just as one of his henchmen shouts that the police are approaching. The crowd panics, and Eddy grabs his bag, attempting to flee. However, fate has other plans, and he is apprehended by the police.
Lucie, the policewoman, corners Eddy on all fronts, knowing about his aliases and scams. She offers him a deal: serve seven years in prison or go undercover at a high school to help her find the child of underworld don, Anton Sagirov. She only has a photo of Sagirov's back and teases Eddy about it. She's received a message indicating that Sagirov has a child enrolled at Charles Baudeliare High School in Lille, whom she hopes to use as leverage to bring the don to France.
Eddy is hesitant, as he doesn't enjoy high school. A flashback reveals that he was once bullied by his peers. Nevertheless, he agrees to the mission to avoid prison. With three weeks left until the students' finals, Eddy also has three weeks to identify Sagirov's child. He adopts the alias Edouard Martin and enlists as a substitute math teacher at the school.
As he enters the school, he finds groups of students milling around the hallway and meets with a security guard. The tension builds as Eddy embarks on this undercover mission, and the episode promises to be filled with surprises and challenges.
Eddy is introduced by a friendly acquaintance, but the guard dismisses him with a nonchalant attitude, suggesting that substitutes are merely fleeting. This leaves Eddy speechless, but he's rescued by Viviane, the coordinator, who speaks in a flurry of acronyms typical of high school staff. However, Eddy finds it perplexing and frequently asks for clarification. She leads him to the teachers' lounge, where a chaotic scene unfolds.
Miss Nora, the history and geography teacher, is visibly enraged at Mr. Pablo, the physics and chemistry teacher, accusing him of stealing her coffee pods without permission. He retorts by labeling her a fascist for her love of control and strict rules. Pablo, the "woke" one, is conscious about people's identities and social causes. Meanwhile, Miss Laurence, the Russian teacher, has her own eccentric thoughts. Lastly, there's Mr. Gilbert, an older biology teacher who's awaiting retirement. He's lost in his own world, lost in his headphones.
On his first day as a teacher, Eddy dives into a sob story about his father who escaped from Bolivia. He tries to identify the "don's child" by asking his students about their fathers and their criminal records. However, his approach is met with disregard and dissatisfaction from the students. This continues for a few more batches with similar results.
At the cafeteria, Eddy meets Florian, the health-conscious PE teacher. He speaks to Lucie on the phone when a student bumps into him, causing him to curse out loud and attracting the attention of everyone in the vicinity. Back in class, Eddy gets into an altercation with Kylian, a student, resulting in Kylian being hit in the left eye and temporarily blinded.
As the episode nears its conclusion, he's summoned to meet the principal. Despite his reluctance to go, he complies with the phrase "when the principal calls, you go." To his surprise, the principal is his ex-girlfriend Tiphaine, who clearly holds a grudge against him for something he did in the past and makes no attempt to hide her disdain for him. She reports him to the police, and Eddy finds Lucie as the police are taking him away. Eddy convinces Lucie to help him out by lying to Tiphaine that they're getting married soon and need the money. Tiphaine reluctantly agrees after Lucie and Eddy perform a fake kiss to convince her of their story.
