After the accidental death of his son on a racetrack, Edward Milan, a wealthy industrialist, asks his nephew to find his grandson, who has been living in an orphanage for eleven years and whose existence he has just learned. But the boy, named Martineau, is suspicious of the police since he has been unjustly accused of shoplifting. He runs away when the two uniforms in charge of taking him back to his grandfather's house appear. He manages to find lodging with an old lady, a kleptomaniac at times, then with a theater prop master who is persecuted by his fiancée and finally with a lonely veterinarian.