Remy is a rat who lives in the attic of a French country home with his brother Emile and a pack led by his father Django. Gifted with a keen sense of smell and taste, Remy aspires to be a gourmet chef, inspired by France's recently deceased top chef, Auguste Gusteau, but instead his talent is put to work in sniffing for rat poison. When the pack is discovered by the home's occupant, they flee into the sewers; Remy becomes separated from the others and ends up marooned underneath Gusteau's restaurant in Paris, conversing with a hallucination of the famous chef.
Urged on by Gusteau, Remy makes his way up to the restaurant's kitchen skylight to watch the staff in action. There, he observes Alfredo Linguini being hired as an escuelerie by Skinner, the restaurant's current owner and Gusteau's former sous-chef. When Linguini spills some of the soup and attempts to recreate it using random ingredients, Remy is horrified, and falls into the kitchen; there, instead of escaping, he fixes the soup. Remy is caught by Linguini just as Linguini is caught by Skinner, but before anyone can stop the serving staff, the soup is served and found to be a success. Colette Tatou, the staff's only female human chef, convinces Skinner to retain Linguini, believing him to be the success behind the soup. Linguini takes Remy home instead of killing him, as Remy was the "little chef" who made the soup.