Code Unknown is a film that follows the intersecting lives of several characters in Paris. Jean, a farm lad, runs away from his silent father to seek refuge with his older brother Georges, who is covering the war in Kosovo. In a moment of anger, Jean throws a bag of half-eaten pastry at a beggar, which leads to a confrontation with Amadou, a young Franco-African.
The police arrive and arrest Amadou, while the beggar is deported. This incident deeply affects Georges's girlfriend Anne, and their relationship is strained when he returns from the war. The lives of these characters are forever altered by the events surrounding the pastry bag.
Throughout the film, we see the repercussions of the incident play out as separate lives intersect for a brief moment. Deaf children bookend the story, using pantomime to express words, feelings, and situations. The film leaves viewers questioning the deeper meaning behind what the children are expressing.