A Mermaid in Paris

On a walk home, Gaspard discovers an unconscious mermaid washed ashore in the Seine and rushes her to a hospital. The attending doctor Victor is hypnotized by her singing and dies suddenly, leaving Lula without admission. Unable to secure care, Gaspard brings her to his apartment and places her in the bathtub.

Lula regains consciousness and attempts to hypnotize Gaspard, but he remains immune to her song. She explains that she must return to the ocean within two days or she will die, but Gaspard insists she stay until her wound is fully healed, deepening their bond.

The next morning, Lula is surprised that Gaspard has not left, and Rossy, his nosy neighbor, visits and believes Lula is his new girlfriend. Rossy tells Lula the story of the Flowerburger and why it matters to Gaspard, adding to Lula's growing place in his life.

Milena, Victor's pregnant girlfriend and a doctor, investigates his death and discovers a pop-up book left behind by Gaspard at the hospital that chronicles the Flowerburger's history. She also finds a gooey blue substance outside the hospital, later identified as the blood of an unknown creature that cannot survive out of the ocean, prompting her to pursue a mermaid sighting.

Lula tries smoking a cigarette left by Rossy and accidentally drops it, starting a fire that nearly burns down the building. Gaspard rescues Lula and moves her to Rossy's bathtub to keep them safe.

Despite the danger, they grow closer, and Gaspard proposes a farewell party at the Flowerburger to celebrate their bond before Lula must return to the sea. The idea to stage a temporary farewell underscores his desire to preserve his grandmother's legacy while keeping Lula in his life.

Gaspard introduces Lula to Camille, who is pleased to see his son connected to someone, while Lula shares that her mother was killed by a sailor and that she has taken revenge on others. Milena arrives at the Flowerburger looking for Lula, beginning to connect the mermaid to Victor's death.

Gaspard leads Lula to a shark tank at the Flowerburger and dives in to swim with her, and they kiss underwater, sealing a fragile romance. The moment heightens Milena's resolve to uncover Lula's danger to Gaspard.

The next morning, Lula's fate becomes urgent as Milena and the biologist return to collect samples from Gaspard's bathtub and declare their intention to stop Lula from claiming more victims. Gaspard faints when Milena demands Lula's whereabouts and is taken to the hospital, where Lula is being kept and her blood drawn for study.

Rossy helps create a distraction as Gaspard leads Lula away from Paris, with Milena in pursuit. He dives Lula into a river and she swims away, while Gaspard faints; Milena hallucinates that Victor is alive and revives him with CPR.

Back home, Gaspard receives a bottle containing Lula's tears of pearls from the biologist, and he uses them to buy the Flowerburger from Camille. With the Flowerburger now his, he prepares to move on to the next chapter with Lula in mind.

Gaspard sets sail aboard the Flowerburger, now his, hoping to be reunited with Lula someday. The final images hint at an enduring love and the possibility of their reunion across the ocean.