Because he was given 50 francs one night as he was reciting poetry in a Parisian café, Grégoire decides to discover the world, and to take his fiancée Micheline alongside.

A horrific and, on the face of it, incomprehensible murder has just been committed on the unsympathetic person of a loan shark. The victim's body is found lifeless, but the circumstances of his death are far from clear. For want of anything better to go on, the police immediately suspect a penniless gentleman who had the bad idea and misfortune to be present at the time of the crime. The police don't take the time to look for other possible suspects, and are not at the end of their surprises. A dark story seems to lie behind this imbroglio of incoherent facts.

Historical film directed and written by Sacha Guitry follows the the history of Paris from its founding through the significant events in the city's history.