Jojo has been living for a while in a room under the roof of a block of flats in Pigalle. He has chosen to leave home since he realized his stepmother has hated him from day one. Among his many neighbors in the house is the gorgeous Jenny Dorr, a nightclub dancer,whose lover he dreams of becoming. But as the boy is only sixteen Jenny proves kind and motherly but that's that. Worse, she becomes the lover of Dicky, a mediocre boxer farting around in the Pigalle cafés. On the other hand, Jojo, who has no income, must absolutely find work, all the more as he woos Marietta, one of his other neighbors, a young lady more suited to his age. Selling magazines works for a while but posing as Narcissus for two gay artists proves a disaster. When things go really awry, Jojo tries to commit suicide by jumping off the roof of his house...