A new pupil, Ben, arrives to the school and becomes good friend with Stefy. Charly is jealous and suspects him. Carl Witt, Ben's father, is accused of stealing some sculptures and the gang tries to prove his innocence ¿ except for Charly, who's convinced Carl is guilty. Ben helps at the investigation, which leads the kids to Tartiflette Art Gallery. Once they solve the case, Carl decides to move again to another city. Stefy is upset, as she will not see Ben anymore.