Gérard Lanvin is being offered a huge part in an American blockbuster about the landing of the Allies in August 1944. The filming takes place in the South of France. On the spot, Gérard meets Momo Zapareto who takes care of the maintenance of the swimming pool of the house which the production has offered him to stay during the filming. But Momo is a fan, a huge fan, too much of a fan. He has seen all of Gérard's films, and very quickly does everything to make himself indispensable in the eyes of his idol and the film crew. For Gérard, the nightmare has only just begun.