Gigot (Gleason) is a mute Frenchman living in the Montmartre district of Paris in the 1920s. He makes a hand-to-mouth living as a janitor at his landlady's apartment building. Though treated with condescension by most of his neighbors (and often the butt of practical jokes), he is much loved by the local children and by animals, whom he often feeds. He seems content with his life, though he has one strange passion: he attends every local funeral, whether or not he knew the departed, marching in the funeral march and crying along with the other mourners.
One rainy evening he is returning home when he comes across a woman named Collette (Katherine Kath) and her young daughter Nicole(Diane Gardner) sitting in a doorway trying to keep dry. He lets them stay at his apartment. Collette is suspicious of Gigot from the start but young Nicole warms to him right away. One of the highest points in the movie is the scene wherein Gleason does a stunning pantomime, Gigot takes Nicole to church only to discover she is unbaptized and completely ignorant of what a church is and unaware of God. Young Nicole points to a crucifix and asks Gigot who that is. Gigot clearly struggling and regretful of his muteness acts out the story of Christ beginning with Mary cradling the baby Jesus, His childhood through to the horror of the crucifixion. When Gigot is through he opens his eyes to see Nicole staring at him with a single tear on her face. Nicole then turns and blows a kiss to Christ on the cross. Gigot oftens entertains the little girl, sometimes by dancing to his old Victrola, and on another by dressing as a waiter to feed his mouse. He is also very protective of Nicole, once running alongside her on a merry-go-round to make sure she doesn't fall off. It is this protectiveness that leads him to prevent Collette from soliciting a john several minutes later on a park bench near the merry-go-round. Gigot is beaten by the frustrated man for his troubles. Furious, Collette threatens to leave with Nicole, but stays when Gigot claims he has money. With an hour to prove himself and uncertain what to do, an opportunity is handed him when he passes by the bakers. The baker and his wife are called away, leaving the till open. Gigot is very reluctant, but steals from the till. He takes broken cookies (to feed to the pigeons) - and leaves the usual steep payment for them!
With his ill-gotten gains, Gigot, Collette and Nicole go on a shopping spree, buying much-needed new clothes for Collette and Nicole and a meal at the local restaurant for all three. Gigot is even persuaded to get a straw boater and a shave. But the good times are not to last - Collette's ex-boyfriend decides he wants her back, and Collette agrees. She wants to take Nicole, but he persuades her to wait til morning. Unknown to her, Gigot sees them leaving together and is heartbroken. The next morning, when Collette returns, she finds Gigot and Nicole missing. The baker discovers the theft, and soon Gigot is a suspect. Morever, two bureaucrats called in by one of Gigot's neighbors have come to (apparently) have Gigot committed. But Gigot and Nicole are only at an abandoned basement, listening to the Victrola while Gigot dances - with a little too much gusto though, as the roof falls in. Gigot is unhurt, but Nicole is unconscious. Frightened, he takes the girl to the church, where the parish priest calls a doctor. Thinking the Victrola may help, he goes back to retrieve it and runs straight into an angry mob. (He needn't have worried: Nicole is not seriously hurt.) The mob chases Gigot to what looks like an old coal loader near the river, Gigot falls into the river and does not resurface. The locals think Gigot is dead, and organise a funeral for him. Gigot is not dead, merely hiding. He sees the funeral march and as always follows, though he keeps a distance. When the time comes for the eulogy, he realizes it is he they're holding the service for, and is moved by what may be their false sentiments. Suddenly, one of the mourners sees Gigot, and the chase starts again.
Gleason had conceived the story himself years earlier and had long dreamed of making the film. He wanted Orson Welles as director, and Paddy Chayefsky as screenwriter. Though Welles was an old friend, the board at Fox rejected him as being an overspender. Gene Kelly was selected as a compromise. Chayefsky was not interested and John Patrick, writer of Teahouse of the August Moon was signed instead.
The film was shot on location in Paris. Most of the production crew and cast were French, some spoke no English. Gleason bore with this in two ways: Kelly spoke French, and Gleason's character had no lines, being mute.
Gleason was extremely proud of the film, which earned one Academy Award nomination for Best Adapted Score. Gleason received a story credit and a music credit. On the other hand, according to the book The Films of Gene Kelly by Tony Thomas, Kelly himself said that the movie "had been so drastically cut and reedited that it had little to do with my version."
The term "gigot" means "leg of mutton" in French. This presumably refers to Gigot's muteness.
French actress Katherine Kath is better known in the US for her high-stepping role as the dancer La Goulue in John Huston's biofilm Moulin Rouge, and from an episode of The Prisoner called A.B. and C., where she played Madame Engadine.