The novel Twilight in Delhi follows the decline of an aristocratic Muslim family in Delhi in the early 20th century. It describes Mir Nihal, the patriarch of the family, his wife Begum Mir Nihal, and their children including his favorite son Asghar. The story explores themes of modernity versus conservatism and the downfall of Muslim civilization in India through the symbolic deterioration of Mir Nihal and his family's circumstances.