L'Assommoir is a study of alcoholism and poverty in the working-class districts of Paris.
Gervaise Macquart, who is featured briefly in the first novel in the series, La Fortune des Rougon, is running away to Paris with her shiftless lover Lantier to work as a washerwoman in a hot, busy laundry. After Lantier leaves her, she swears to never fall in love again. Until she meets Coupeau, a teetotal roofer and loving partner, whom she marries. Gervaise is enjoying the highs and lives her dream life as she opens her own laundry and their daughter Anna (nicknamed Nana) is born.
Later Coupeau suffers an injury und gives up to the alcoholism. From that moment their life goes downward, experiencing several embarassing failures, ending up with irreparable debt and irrecoverable tragedies.