Twilight in Delhi focuses on an upper caste Muslim family over a number of years in early 20th century Delhi. The drama of their personal lives reflects and intersects with the larger sociopolitical changes occurring in the city.
As the story begins, husband and wife Mir Nihal and Begam Nihal are preparing to find a wife for their son Asghar. He is in love with his friend Bundoo's younger sister Bilqeece, but because she belongs to a lower caste, he feels it is unlikely that his parents will consent to the match. His father already disapproves him of spending so much time with Bundoo, and their relationship is further strained because Asghar has begun dressing in English-style clothing. Still, he is determined to be with Bilqeece at all costs. He sends a letter to his sister Begam Waheed, who lives in another city with her husband's family, telling her to come to Delhi at once to help him with a matter of great importance. When she arrives, he explains the situation, and though she is initially hesitant to help him, feeling that he could find a more suitable wife, she acquiesces when he threatens suicide. She feels the threat is not idle because Asghar has had very little go his way in life, and he seems truly desperate. She brings the matter up with Begam Nihal, who similarly does not agree Bilqeece is the right woman for Asghar. However, Begam Nihal comes to understand that her son is serious about committing suicide, and in an effort to save him, resolves to convince her husband to consent to the match. When he is made aware of the situation, Mir Nihal is much less sympathetic to Asghar's plight, and says he would rather his son kill himself than dishonor the family by marrying below his status. Though she does not receive his consent, Begam Nihal decides to go ahead with the proposal anyway, believing that her husband will come around eventually. Meanwhile, Asghar is sent away to live with Begam Waheed so as to avoid his father's ire until he accepts the match.
Mir Nihal's days involve going to his lace shop during the day, stopping to see his mistress Babban Jaan, and then coming home, where he tends to his pigeons. Flying pigeons is a very popular pastime in Delhi, and Mir Nihal has one of the most fearsome flocks in the city. They are very well trained and often attract pigeons from other flocks. One day, after buying some new pigeons, he is informed that Babban Jan, who has been ill, has taken a turn for the worse. He rushes to see her, but it is too late, and she has passed away. He returns home and realizes that in his haste to see Babban Jan, he forgot to close the door to the pigeon house, and as a result some cats were able to get in and feast on his birds. Only a select few pigeons survive the attack, and Mir Nihal is so devastated that he decides to let them go and permanently give up pigeon flying. Reflecting on the hardships of life, he realizes that it is silly and futile to stop Asghar from ruining himself and his status by marrying Bilqeece. Though he is still opposed to the match on principle, he no longer wants to fight about the matter, and gives his consent. Later, Asghar, who had found himself a job while he was away, returns home for Ramazan, and offers his father some money as a sign of respect. Mir Nihal appreciates the gesture, and forgives him.
Preparations for the marriage begin, and it is planned for December of 1911. It is the same month that the British authorities plan to hold a ceremony in Delhi in honor of the coronation of a new king. Known as the Durbar, it attracts many people from around India. The residents of the city have mixed feelings about the event and about the British, whom they call Farangis, in general. Some are appreciative of the business which the Durbar is attracting to Delhi, and are willing to entertain the idea that British rule will bring India greater prosperity. Others remember the brutality of the regime in 1857, when the Mughal Empire was overthrown, and are disgusted by all the excitement surrounding a celebration of a foreign ruler. Mir Nihal falls under the latter group, and though he attends the Durbar with his family, the whole affair saddens him deeply, reminding him of how India once had its own kings, and how the country's former glory has been diminished under colonialism.
The day of Asghar's wedding arrives, and it is a huge affair, with countless guests in attendance. There is some tension between the bride's family and the bridegroom's family, as one of Asghar's cousins offends one of Bilqeece's cousins by playing a practical joke on him. However, the offended party eventually evens the score, playing a practical joke of their own, and the wedding otherwise proceeds according to plan. Asghar is overjoyed to be marrying the woman of his dreams, though he also feels a twinge of melancholy at the major life change he is undergoing.
As Asghar and Bilqeece adjust to married life, some problems arise. Bilqeece is very shy, and less romantic than Asghar had imagined. She worships him like a God, but she has trouble expressing her love. She had been raised by a religious aunt, who taught her to be a proper wife but not to show her feelings, as that would be unseemly. Still, they are mostly happy together. Though Begam Nihal grows to like her, Mir Nihal takes much longer to accept his daughter-in-law, eventually only doing so after she cooks him a special meal.
Bilqeece gives birth to a child, and, after her father dies, she and Asghar move into a house adjoining her mother's house. Asghar is affectionate with his daughter, but has grown cold toward his wife. He feels she no longer has time for him, and he has begun paying more attention to their maidservant. Bilqeece is frequently ill, and spends most of her time in bed. It seems she has lost the will to live. Many hakims and fakirs, traditional Muslim healers, are sent to find a remedy for her condition, but nothing helps. One night, Asghar finds her in an especially pitiful state, and realizes how callous he has been toward the woman he once loved. He apologizes for his behavior, and promises to get her a doctor, one trained in modern medicine, the next day. He does, and Bilqeece is diagnosed with tuberculosis. Her prognosis is positive, though, and she is given medicine to get better. More importantly, however, Asghar's change in attitude toward her has helped her regain her desire to live.
Meanwhile, World War I has begun, and many Indians have joined the British army for pay. Mir Nihal suffers a paralytic stroke, and though he slowly recovers some mobility, he is mostly confined to his bed. Begam Nihal feels sorry for her husband, and does her best to help him, but she is losing her eyesight and it is more difficult for her to do her usual household tasks.
Some years pass, and though the war has ended, death is still a constant presence in Delhi due to the spread of the Spanish flu. There is no space left to bury the dead, and people are price-gouged for various aspects of the burial process. The feelings of dread which Bilqeece once had while she was sick with tuberculosis return, and, indeed, she catches the flu. After a long battle with the disease, she passes away. Asghar is devastated, and visits her grave every day.
The Home Rule Movement has begun, and as a result, Delhi has become a site of tension and civil unrest. Though Mir Nihal hates the British, he feels the current movement is not for him. Many of his friends have died or no longer come around, and he sees the Delhi that he once knew disappearing for good, replaced by a city and culture that combines aspects of both Indian and British society.
Six months have passed since Bilqeece's death, and Asghar has taken on many of the responsibilities of childcare which are typically the duty of the wife. Bilqeece's younger sister, Zohra, often helps with the child, looking after her while Asghar is at work. One day, she sees Asghar looking sad and desperate, and while attempting to comfort him, admits she has feelings for him. He too realizes he has his feelings for her, but she is embarrassed, and runs off. Though she avoids him for a while afterward, he eventually confronts her, and they begin a love affair. He wants to marry her, and seeks approval for the match from his parents, presenting it to them as a matter of convenience, a decision made out of concern for his child's well-being. Through Mir Nihal's gossipy sister-in-law, Begam Jamal, news of the intended proposal gets back to Bilqeece's mother, Begam Shahbaz, who is angry that Asghar would have moved on from his wife's passing so quickly. She forbids Zohra from continuing to visit Asghar, though they still see each other in secret.
Through Zohra, Asghar learns that Begam Jamal had babbled to Begam Shahbaz, and he complains about Begam Jamal's meddling ways to Mir Nihal. Mir Nihal is also furious with his sister-in-law. A servant overhears his words of anger, and tells Begam Jamal, who is deeply offended, and confronts her brother-in-law. She tells him she will leave their household unless he reveals the source who informed him of her discussion with Begam Shahbaz. He refuses to give away his son, and she moves. Mir Nihal is shattered by this event. Begam Jamal had lived with them for 40 years, ever since her husband, Mir Nihal's brother, had died. He sees her departure as a further sign that the world he and his brother grew up around has gone for good.
Habibuddin, Asghar's older brother and a beloved member of his community, becomes sick, and he returns home for treatment. Many hakims and fakirs visit him with one remedy or another, but his condition does not improve. Once again, Asghar sends for his doctor, and Habibuddin is diagnosed with tuberculosis. This time, however, the medicine which the doctor prescribes does not work, and Habibuddin dies. The whole family is crushed by his loss. When Asghar returns from the funeral, Zohra's maidservant is there to meet him with a letter from Zohra. Zohra's mother has found her a match, and the marriage will occur in the next day.
Asghar is shellshocked, both by the letter and the loss of his brother. Mir Nihal is also in a state of despair. He feels that there is no beauty left in this world.
