Horty (Olivier Martinez), a young French foundry worker in 1912, wins an all-expenses-paid trip to Southampton to witness the maiden voyage of the RMS Titanic. At his hotel, he meets Marie (Aitana Sánchez-Gijón), a beautiful young woman who claims to be a chambermaid on the luxury liner. Lacking a room for the night, Marie stays in Horty's room; they share a night of intense conversation, emotional intimacy, and a mysterious kiss before she disappears onto the ship the next morning. Upon returning home to his jealous wife, Zoé (Romane Bohringer), Horty begins telling fellow factory workers romantic stories of his night with Marie. As his tall tales grow into elaborate, erotic myths, they blur the line between reality and fantasy, captivating the entire town while straining his real-world marriage.