Le grand soir is a dark comedy film that tells the story of two estranged brothers: the first, named Not, is an ageing punk who lives in a campervan with his dog, and the second, Jean-Pierre, is a father and a tight-suited conformist. Not is unemployed and disenchanted with society, while Jean-Pierre works as a salesman at a mattress store and leads a mundane life with his family.
One day, Not and Jean-Pierre decide to reunite and plan to seek revenge on the shopping mall that brought nothing but misery to their lives. The mall is owned by a wealthy family, the Comtesse, who represent the epitome of capitalist greed and excess. Not and Jean-Pierre's plan involves setting the mall on fire and causing chaos on the night of its grand reopening.
As the brothers prepare for their act of rebellion, they confront their differences and reflect on their past with their parents and childhood. The film also introduces various eccentric characters, such as a young girl who is obsessed with death and a group of anarchists who live in a nearby commune.
Throughout the film, Le grand soir offers a satirical critique of consumerism, conformity, and the absurdity of modern society. The film's surreal and darkly humorous tone, combined with the outstanding performances by the two main actors, make it a unique and thought-provoking viewing experience.