In 1910, during the Great Flood of Paris, shy projectionist Emile Petit and his friend Raoul travel to the Botanical Gardens to make a delivery.

Raoul experiments with two potions: "Atomize-a-Tune", which endows its users with operatic voices, and "Super Fertilizer", which makes plants grow to enormous sizes.

Lucille, a cabaret singer at the club L'Oiseau Rare, faces pressure from her aunt Carlotta to marry the wealthy Police Commissioner Victor Maynott, a mayoral candidate.

[4] Bergeron says he was mainly influenced by Franquin the graphics of the characters, and draws his inspiration from impressionist painters like Alfred Sisley for the color moods and decorations.

[5] The appearance and gestures of the monster and the singer Lucille are respectively inspired by those of Matthieu Chedid and Vanessa Paradis, who lend them their voices in the French dubbing.

[4] Bergeron even had to put the project on hold for nine months because he struggled to raise funds; he is fortunately advantaged by his past experience at DreamWorks.

[6] Among the best reviews is that of the free daily 20 minutes, which sees the film as a "little gem of poetry full of charm and songs" , whose critic praises the "fanciful universe steeped in humor and originality".

[7] In Le Figaroscope , Emmanuèle Frois provides a very favorable review, where she appreciates the originality of the story, the pure moment of poetry created by the music of -M- and the successful duo formed by Matthieu Chedid and Vanessa Paradis ; she only regrets the small number of these songs.

[8] In La Croix, Corinne Renou-Nativel gives a very positive review, where she appreciates the visual universe of the film, the "chiseled" dialogues and the story "without downtime"  ; she concludes by indicating that "the notes of humor, the freshness of the images, the captivating duo formed by -M- and Vanessa Paradis, the poetry which surrounds everything make this film a nice meeting for adults and children.

[9] In the television supplement of the weekly Le Nouvel Observateur (TéléCinéObs), Xavier Leherpeur gives the film two stars out of four: he considers it "brimming with visual discoveries, humor and poetry" , and appreciates its universe and the music, but judges the final sequence "less grandiose than it could (and should) have been".

[10] In the daily Le Monde, Thomas Sotinel judges the story "strange and not very coherent" and believes that the film suffers from its lack of resources compared to big productions from American studios like DreamWorks ; he concedes to the film a capacity to awaken the spectator's "appetite for the marvelous" , but regrets that this appetite is often frustrated.

[12] The critic from Ouest France , who gives the film two stars out of four, sees in the scenario "yet another variation on a somewhat worn-out theme" and regrets that the film concedes too much to Hollywood conventions, without sufficiently developing the French touch of the story, so that the result is judged "too wise and too [restrained] in its formatting"  ; the article however appreciates the quality of the original soundtrack.

[13] In Britain, where the film was released late January 2012, A Monster in Paris received a fairly good reception in the press.