It is certainly an epic depiction of living in a rural slum, with all its workshyness, filth, poverty, vile smells, lack of modern gadgets*, theft, casual rape, violence in general, frequent lack of food, lack of communication, lack of articulacy, lack of interest, etc. This is a kind of social horror story which wouldn't appeal to anyone who prefers feelgood fare with happy endings.
In a town up a mountain there is a farm mis-run by the mother and father of young Marc and Simone, with the grandparents (grandfather and M'mé Coche (his second wife)) living nearby –in similar squalor. The father seems not to like work much, is tyrannical and violent, and has a voracious sexual appetite, which is apparent from his regularly raping the young milkmaid Mado while she's milking a cow. The reader can't fail to agree with her when she calls the family completely mad and announces that she's leaving. Only, when she leaves she also takes what little savings the family has, and nine months later leaves her and the father's baby (whom she's called Monue) at the entrance to the farm.
Monue becomes part of the family and proves to be a revelation to Marc – a great change from his smelly one-eyed sister Simone – who's nicknamed 'Pue-la-Pisse' at school. And the lovely Monue and dreamy Marc become great friends.
The family leave the heights for the lower village Le Bas, although for reasons of space they also have to leave Monue in the care of the grandparents. But things get worse: although the father has a (very low-paid) job, he can't do it without taking a bottle of wine with him, and his drink-fuelled violence at home not only leads to him hitting members of the family but to a savage attack on the cow. Then the grandfather dies and – much to Monue and Marc's delight – the half-siblings are reunited, with Marc sleeping in the van. Later, Monue joins him in the van and the two enjoy a chaste sleeping relationship until the break comes when the unthought-of happens and Monue starts menstruating. And Marc starts going mad because his great childhood friend is not longer a little girl. Then, the blood really hits the fan, but I'll leave this fascinating (and often disturbing) novel there.
*At first the novel seemed timeless, although the existence of the petrol-driven van and mention of washing-machines set it in a more modern context.