 Now Christmas is approaching, Jeanne and Lus decide to organize a seasonal party for everybody before the students return home for the holidays. A misunderstanding causes Dieter and Hugo to suspect Gentil, who is rehearsing for his vocal Holy Night recital, and vice versa. Jeff has invited Gust, the pyrotechnician who will illuminate the billiards club s Christmas party, but passes him for a homeless so Jeanne will welcome him and tricks dumb Hugo into handing over his room, so the fireworks can be prepared. Lies and misunderstandings keep piling up as the party approaches, especially when Odilon slips Gust has caused several fires so she thinks he s a pyromaniac, and just when Gentil starts singing things explode...