Momo is ten years old, or thereabouts, and has his whole life ahead of him, unfortunately. He lives in Madame Rosa's house, on the sixth floor of an apartment building without an elevator, in Belleville, Paris.

Madame Rosa is a seventy-year-old, overweight, Jewish former prostitute, who keeps something like a boarding house in her apartment for children whose prostitute mothers are away for work. In the same building lives Madame Lola, a transvestite, former boxing champion in Senegal. And Mr. Hamid, a carpet merchant, who is always smiling, even though he says that no one can live without love. And Mr. Waloumba, who came from Cameroon to Paris to be a street sweeper, but he also has a flamethrower license and breathes fire from his mouth.

When he learned that Madame Rosa kept him at her home because she received a monthly remittance and not because she loved him, Momo was saddened. But he was wrong, Madame Rosa loved him very much.