During the Second World War, Georges Masse undergoes a dangerous mission by taking secret documents from Tangiers to London.

Alain Resnais & Robert Hessen use the famous Picasso mural "Guernica" in combination with newspaper headlines in an anti-war cry against the Spanish Civil War. Narration by Jacques Pruvost highlights the Guernica atrocity of April 1937, followed by a poem by Paul Eluard read by María Casares to a discordant score by Guy Bernard.