So Long a Letter begins when Ramatoulaye, a Senegalese woman living in Dakar, the country’s capital, decides to write a letter to her old friend Aissatou, who lives in America. The letter is occasioned by the sudden death of Modou, Ramatoulaye’s estranged husband. In keeping with Muslim custom, Ramatoulaye must observe a mirasse, a forty-day period of isolation and mourning. Over the course of this period she keeps a diary, which she eventually intends to send to Aissatou.
Ramatoulaye begins by reflecting on the long funeral proceedings following Modou’s death. Senegalese-Muslim customs dictate that Ramatoulaye serve as a host to all the mourners and well-wishers, opening her house to them and providing them with food and drink. This strikes Ramatoulaye as a grave injustice, as Modou, in his final years, wanted nothing to do with her. The mourners virtually sack her house, and though they bring gifts—mostly bank notes—the most of them end up in the hands of Modou’s second wife, Binetou, and her greedy mother (Lady Mother-in-Law).
Ramatoulaye goes on to reflect on her marriage to Modou. She cannot understand what led him to lose interest in her. Their first years together, as sweethearts and then as a young married couple, seemed hopeful. They married despite the protestations of Ramtoulaye’s family, who saw Modou as something of a loaf. In her diary she admits that they were right, and wonders why, despite her education, she chose him over the more sensible option—Daouda Dieng, an older and more established, financially stable man.
Aissatou’s marriage, like Ramatoulaye’s, also disintegrated. Around the time that Ramatoulaye married Modou, Aissatou married Mawdo, a medical student and overall model citizen. The two were greatly in love. However, Mawdo is of noble birth, while Aissatou is merely the daughter of a goldsmith. Mawdo’s family—in particular his mother, Aunty Nabou—objected to the union. In an effort to undermine the marriage, Aunty Nabou traveled to her ancestral hometown and convinced her brother to relinquish one of his daughters—Aunty Nabou’s namesake—to her care. Aunty Nabou proceeded to raise and preen young Nabou. Then, when the girl was of proper age, Aunty Nabou begged Mawdo to take young Nabou as his second wife. Mawdo, fearing that his mother would become distressed and fall ill if he declined, agreed. He assured Aissatou that he did not love young Nabou, but he also had children with her. Aissatou could not accept this and divorced him. She focused on her education, received a degree in diplomacy, and moved to America to work in the Senegalese embassy.
Meanwhile, Ramatoulaye was enduring her own marital misfortune. Her daughter Daba befriended a girl name Binetou. Binetou spoke often of a “sugar daddy,” an older man who bought her clothes. After a while, Binetou’s family began to pressure her into leaving her education behind and marrying the man for his money. Binetou reluctantly agreed. Ramatoulaye was disappointed by this news, but not otherwise suspicious. Some days later, Mawdo, Modou’s brother Tamsir, and a local Imam appeared at Ramatoulaye’s house. Together they informed her that Binetou’s sugar daddy was in fact Ramatoulaye’s husband Modou, and that Binetou would soon be her co-wife.
Ramatoulaye was left heartbroken and effectively abandoned as Modou began a new life with Binetou. Despite this, she decided to remain married to Modou, accepting her fate as if it were a duty to fulfill. Her children protested, but she remained steadfast.
Now Modou has died, and Ramatoulaye must navigate the strange situation of being forced to mourn for a man who abandoned her. As her mirasse draws to a close, she is approached by Tamsir, who announces that he will marry her. Ramatoulaye is deeply offended by his crass proposal, and tells him off in front of Mawdo and the Imam. Later, Daouda Dieng proposes to her. Though he does so with considerably more tact than Tamsir, Ramatoulaye rejects him as well. She resolves to focus her efforts on raising her children.
Thanks to the increasingly prevalent forces of modernity, Ramatoulaye’s adolescent children become exposed to a host of new dangers, dangers from which she feels they must be protected. While playing baseball in the street, two of Ramatoulaye’s sons are run over and injured by a wayward motorcycle. She catches three of her daughters smoking. Aissatou’s namesake gets pregnant out of wedlock. Ramatoulaye responds to all of these crises with strength, equanimity, and poise.
Ramatoulaye concludes her long letter by anticipating Aissatou’s impending return to Senegal. She looks forward to seeing her friend, and trusts that despite the physical changes they’ve endured, their friendship will be strong as ever.