Despite Lise's advice, Claire decides to celebrate Christmas with Leon, a young outcast who claims to live outside the system. They agree to organize an anticapitalist Christmas Eve, prohibiting all expenses. Meanwhile, Mathias delivers presents as Santa for a well-paid temporary assignment.
Jean is a "slow" man, he builds his life around his anxieties, and considers himself unsuited to life in society. He lives with Alex, who is a "fast" man. Passionate about aerodynamics and eurodance, Alex lives fast and asks himself as few questions as possible. One morning, he receives a fast friend, Lou, at their place, while Jean had also planned to receive a slow friend, Caroline.