As a child, Kanai learned that Kusum’s father died searching for firewood in an off-limits area, which left her mother very poor. As a result, Kusum’s mother traveled to do housework, though Horen realized she was probably trafficked. Horen had brought Kusum to Lusibari and left her with the Women’s Union to protect her. Despite the rough beginnings of the relationship, Kanai and Kusum became friends. Nonetheless, the difference in their backgrounds is apparent: Kanai realizes that if Kusum visited him in the city, she’d be mistaken for a maid. Kusum introduces Kanai to The Glory of Bon Bibi, and the two watch a performance of it together. The play tells of a Muslim man, Ibraham, who fathers two blessed twins, Bon Bibi and Shah Jongoli. The twins were sent to the Sundarbans to make them habitable, and encounter a demon king. Bon Bibi draws a line through the region, and humans settle in her half of the area. But eventually, a man named Dhona led a group into the jungle in hopes of getting rich, taking a boy named Dukhey with him. Dukhey’s mother had instructed him to call on Bon Bibi if he needed help. Arriving in the demon’s territory, Dhona sees strange things, and eventually the demon comes to him in a dream, promising him riches in exchange for Dukhey. Dhona abandons Dukhey on the shore, but when Dukhey calls out for Bob Bibi, she immediately saves him. Kanai falls in love with the play and sees it many times. At the last performance, however, he falls asleep and awakes to Kusum crying. She explains that she called for Bon Bibi when her father died, but she never came and he was killed by a tiger.
Piya wakes up in the middle of the night and realizes that Fokir is awake as well, keeping watch, which moves her, since she realizes he wants to protect her. She begins to shiver, and Fokir lies down next to her to warm her, but they soon both jump up, uncomfortable with their closeness. Fokir leaves to see his son, and Piya, who’s using the sari as a pillow, wishes she could tell its owner (presumably Fokir’s wife) that nothing sexual happened. Piya awakens again to thick fog and stays in bed, resting. Then, she hers Fokir drop anchor and is jolted awake by the sound of Orcaella dolphins, and excitedly calls Fokir. Yet he seems unsurprised, which puzzles Piya—the dolphins are known to be unpredictable. She is further confused when she realizes that the dolphins—seven in total—don’t leave the crook of a river where they are located, which is unusual for the species.
Kanai wakes up and finds Nilima looking sick, but she insists it’s just a cold. She’s nonetheless excited to hear about Nirmal’s packet, but disappointed to find it only contains a small notebook. She is also surprised that the writing is dated to 1979, since that was the year of Nirmal’s death, when he was often unstable and incoherent. Kanai explains that the notebook was written in May of that year on Morichjhãpi, and Nilima explains that Morichjhãpi had been set aside for tiger conservation until refugees began to move there in 1978 because of the harsh conditions in their camp in central India. Authorities clashed with them many times, and the last clash occurred in May 1979, though Nilima doesn’t know if Nirmal was present for it since his life was very secretive at the time. Emotional, Nilima explains that Nirmal was fascinated by the island because of the refugee’s revolutionary spirit. She recalls how Nirmal accused her of betraying their ideals when she tried to talk him out of his obsession, and wonders aloud if this dispute is why he left the notebook to Kanai instead of her. Kanai asks if Kusum is related to Nirmal’s obsession with the island, and Nilima flinches. She explains that in 1978, Kusum came to Nilima, hoping for medical help on Morichjhãpi, but Nilima insisted she couldn’t interfere. That was the last time Nilima saw Kusum, who later died in a massacre at Morichjhãpi.
As the tide rises, Piya begins to see fewer dolphins. Though she initially thought the dolphins were migrating, she begins to question this idea. Some Orcaella dolphins like coastal saltwater, while others prefer freshwater rivers. The latter ones are more territorial and return to the same location every year. Though Piya expected to see coastal Orcaella, the dolphins she saw didn’t behave like coastal ones, but the water in the area is also too salty for freshwater dolphins. She begins to wonder if the Oracella in the area migrate every day instead of just twice a year, a theory that would have broad implications if proven true.
Piya continues to think about this theory. Because the water in the Sundarbans is a mixture of saltwater and freshwater, regions within the water have varying levels of salinity. But to study the dolphins scientifically, Piya would need decades. Piya is conflicted about this prospect: she was drawn to field biology because of the varied lifestyle of travel it offered, but the stability of knowing that her future could be decided is also appealing.
The story of Bon Bibi means very different things to different people. Though it’s simply an entertaining distraction for Kanai, many of the characters believe in Bon Bibi fully and turn to her in times of desperation. Bon Bibi gives them assurance that they can hold at least some power over the natural world, which constantly threatens to destroy them. Yet Kusum’s story about her father’s killing shows that this faith doesn’t always translate into reality: after all, Bon Bibi didn’t save her father.
Piya’s thoughts about wanting to communicate with the owner of the sari, who’s likely Fokir’s wife, indicate that she may be viewing him as a potential romantic partner, which is a testament to the power of their communication despite the language barrier. In only a day, she’s begun to feel close to him. Her surprise at the dolphins’ behavior also underscores Fokir’s value: while she has formal education about the dolphins, his practical knowledge of them may prove to be more useful. Additionally, this surprise shows that science isn’t perfect, and that the natural world is difficult to understand for even the most educated. Yet because of her training in science, Piya is willing to reevaluate what she knows and formulate a new hypothesis.
Nilima’s insistence on adhering to Nirmal’s last wishes and not reading the notebook but rather letting Kanai do so shows how dedicated she is to her late husband despite their difficult marriage. Though Nilima is pained that Nirmal didn’t want her to read the notebook, she agrees not to read it, even though he wouldn’t know if she did. Nirmal’s character is complicated when Kanai mentions Kusum and Nilima’s reaction suggests that he may have had feelings for her. Thus far, Nirmal has appeared to be a passionate revolutionary who was drawn to Morichjhãpi to realize his ideals. Yet if he was in love with Kusum, he may have gotten involved with the island for entirely different reasons.