The Hungry Tide is set in the Sundarbans, an archipelago of rivers in the Bay of Bengal. Kanai, a wealthy New Delhi-based interpreter and translator and Piya, an American cetologist, first meet on a train to Canning. Kanai is traveling to visit his aunt Nilima on the island of Lusibari to read a packet of papers his late uncle Nirmal left him. Piya is traveling to the same area to survey the Orcaella river dolphins. Before they depart the train, Kanai invites Piya to visit him in Lusibari. Kanai then meets his aunt Nilima on the station platform and they continue to Lusibari by the river. Piya leaves Canning station and obtains a research permit from the Forest Department on the grounds that she is chaperoned by a forest guard. She meets a steamer-boat pilot, named Mej-da, and the three of them set sail.

Kanai and Nilima arrive on Lusibari and head to the Badabon Trust compound where Nilima lives. Nilima tells him that Moyna, a trainee nurse at Lusibari hospital, will have prepared him a meal. Moyna is married to a fisherman named Fokir who is the son of Kusum, a friend of Kanai’s when he was in Lusibari as a child. Nilima leaves Kanai to settle in on the upper floor which she runs as a guest house for Trust visitors.

Piya feels uncomfortable being alone with Mej-da and the guard, and when their steamer approaches a fishing boat, she is shocked when the guard threatens the fisherman and steals money from his young son. Piya, attempting to replace the stolen money with some of her own, is knocked overboard by the guard. She is rescued by the fisherman and decides to continue the rest of her trip with him.

After leaving his belongings in the guest house, Kanai enters his uncle’s study and finds the packet which contains a notebook written by his uncle Nirmal while he was on Morichjhapi island in May 1979. There is also a letter, addressed to Kanai, in which Nirmal asks him to ensure that what he is about to write is never forgotten.

As Mej-da’s steamer disappears from view, the fisherman introduces himself, Fokir, and his son, Tutul. He is considerate and respectful, creating a private space for Piya to bathe, and making her a meal. The following day he takes her to the island of Garjontola, where there is a group of Orcaella dolphins. Piya is surprised as they are behaving unusually and she realizes there is still a lot to learn about the species. But, when she is almost caught by a crocodile she and Fokir decide to set sail for Lusibari.

Kanai spends several days reading Nirmal’s notebook and about the events on Morichjhapi which led to Kusum’s death. Nirmal and Horen were surprised to find Kusum on the island when they sought shelter from a storm there. Nirmal was excited to learn about the communist society being developed by the settlers and wanted to be a part of it. But, when Nilima told him to stay away he was forced to keep future visits a secret. When attempts to scare the settlers away failed, Horen, discovered that the government planned to use extreme force and he and Nirmal returned to Morichjhapi to warn Kusum. It was there that Nirmal wrote in his notebook. He went missing after the massacre and was found, weeks later, in Canning. He returned home but died only months later.

When Piya arrives in Lusibari Nilima invites her to stay in the guest house. The following day, she and Kanai visit Moyna and Fokir and, when Piya asks Fokir to take her back out on the river, Kanai decides to join them. Horen agrees to take them out on his bhotbhoti, the Megha, and Fokir will follow in his smaller boat. On the trip, Kanai is jealous when Piya tells him that working with Fokir has been one of the most exciting experiences of her life. He responds cruelly telling her she and Fokir have nothing in common. Piya is dismissive but, after Fokir assists in the killing of a tiger, she wonders if he was right. When Kanai comes face-to-face with a tiger himself he is shaken and asks Horen to take him back to Lusibari. Horen tells Piya that he will return the next day but, on the way back to Lusibari, he hears that a cyclone is advancing and turns the Megha around immediately. But, when Piya and Fokir have not returned by the following morning, Kanai and Horen are forced to head back to Lusibari or they will be caught in the cyclone themselves. Kanai loses Nirmal’s notebook in the floodwater but, back in Lusibari, promises Nilima he can rewrite it from memory.

Piya and Fokir have spent the day tracking the Orcaella dolphins. When they realize there is a cyclone approaching they head to the closest island where Fokir ties them both to a tall tree with a sari. They cling to the tree as a tidal wave hits but, when the wind changes direction, Fokir is crushed by a heavy object. Piya, shielded by Fokir’s body, survives and is rescued by Kanai, Horen, and Moyna. Piya stays in Lusibari for two weeks, taking care of Moyna and Tutul, and then leaves promising she will be back. It is only two weeks later when she returns and tells Nilima of a conservation grant she has been offered. She would like to share the funding with the Badabon Trust and plans to name her research after Fokir.