The film tells the grotesque story of a large family living in an extremely poor shantytown of the periphery of Rome. The main protagonist is one-eyed patriarch Giacinto (Manfredi). Four generations of his sons and relatives are cramped together in his shack, managing to get by mainly on thieving and whoring, among other things more or less respectable.
For the loss of his eye, an insurance company has paid Giacinto a large sum. Moved by greed, the whole family (including his wife, who is enraged by Giacinto's bringing home a fat prostitute he has fallen in love with, and who has become his mistress) try to poison him in order to inherit the money. However, Giacinto survives. In a frenzy of anger, he sets fire to his home and shoots one of his sons with a hunting rifle (the son survives).
In the meantime Giacinto has sold the house to a Neapolitan immigrant family. The film ends with Giacinto living in a newly built exceedingly crowded shack with both his mistress and his wife, together with an apparently reconciliated family and the newcomers as well.