Jean-Pierre Leaud lives in a garret in Pigalle, the heart of Montmartre. His widowed father has taken up with a woman, and Leaud walked out to make his own way,but it's a ot harder than he ever thought. Alternately a fast-talking braggart, and a helpless child, he has a crush on exotic dancer Magali Noël that lasts until she takes up with washed-up boxer Pierre Mondi. Then it's the young neighbor Monique Brienne, but he's broke and too embarrassed.
Leaud had just begun his career as Truffaut's alter ego, but here under the direction of Julien Duvivier he gives a clearer portrayal of a street kid, sixteen years old, knowing exactly how the world should run and unbearably angry over the fact that it doesn't. Duvivier's Montmartre is just as reckless as it had been in the previous century, but now the locals wear ties and jackets and aspire to get out; but their world is even more circumscribed.