The story unfolds in an immense archipelago of islands, the Sundarbans, between the sea and the plains of Bengal on the easternmost coast of India. Without clear borders to divide salt and fresh waters and with islands criss-crossed with man-eating tigers and huge crocodiles, in decades past a visionary Scotsman founded a utopian settlement where people of all races, classes and religions could live together. However, with the arrival of the good-intentioned Piyali Roy of Indian descent but still stubbornly American, and her scholarly pursuit of the rare river dolphins, the ecobalance of quiet community begins to fragment.
As as cetologist seeking the rare and elusive river dolphins, Piya hires Fokir, an illiterate peasant man, to guide her through the backwaters to map out the dolphin's territory, while Kanai, an older businessman with some infatuation with Piya's youth and drive becomes her translator and mentor of sorts, and so the tides of life begin to turn.
The women in the fishing village where Piya ended up were unusual in that during the day they were devoid of marital reds. Because fishing took the lives of many men, women in their twenties and more fortunately in their thirties would become widows, and so as soon as their men left to go fishing (what other livelihood could there be in this remote island region?), the women changed to saris of white mourning, removed the bangles from their wrists and washed the vermilion from their hair as if to ward off the evil eye and hold misfortune at bay. Shedding the symbols of marriage would have been unthinkable in other parts of India, but here it was done with hopes of preventing bad luck.
It was the freshwater Gangetic dolphins, discovered by William Roxburgh, that were said to explicitly delight in the freshwaters of the Ganges and cavort in the labyrinth of rivers and creeks in the South and Southeast of Calcutta that drew Piya to the backwaters. Once in contact with Fokir who knew the tide waters intimately and had an immediate connection to Piya, she was taken to see the rare elusive dolphins. Orcaella were of two kinds: one liked the salt waters of the coast while the other preferred the rivers and fresh water. There seemed to be no biological difference but rather a choice based on habitat selection, and while the numbers of salt-water preferring dolphins were in the thousands, those preferring the fresh waters were in the mere hundreds and were a fast dwindling breed.
Before coming to these tide waters, Piya had already spent three years working as an Orcaella specialist. She had worked everywhere the Irrawaddy dolphins were found - Burma, northern Australia, the Philippines, coastal Thailand, everywhere in fact except where the first entered the record-book of zoological reckoning: India. Now she was here.
Piya learns more about herself and her choice in studying cetology as she encounters the strangely remote island world of ebbing salt waters. Born in July, her zodiac sign is the crab and she had always wondered why, of all the many interesting animals in the world, a society would choose to honor a crab every twelve years, but in the coastal labyrinth of islands she begins to understand. Crabs are launderers of the mud, scrubbing it grain by grain. Their feet and sides are lined with hairs forming microscopic brushes and spoons. They are a sanitation department and a janitorial team rolled into one - they keep the mangroves alive by removing leaves and litter, and without them the mangroves would choke in their own debris. In fact, they comprise a fantastically large portion of the coastal waters biomass. They likely outweigh the trees and the leaves. They are keystone builders and caretakers of the biomass and should therefore have more recognition than crocodiles, tigers and dolphins who seem to get by far the largest portion of research attention. Ah, and if Fokir hadn't been in pursuit of crabs, she wouldn't even be aware of the vicinity of the dolphins. Maybe the ancients had gotten it right after all - perhaps it was the crabs that rule the tide of her destiny.
Ah, but tigers played a big role to in the balance of the ecosystem. The Sundarbans were remote and official research was sketchy but the wife of the Scotsman who had initially established the utopia had been keeping records for years on tiger killings and it was her guess that among the network of islands, one person a day was killed by tigers. Though the number was shocking, the woman referenced 4,218 humans killed by tigers in lower Bengal between 1860 and 1866. The number was compiled by J. Fayrer, the English naturalist who coined the phrase "Royal Bengal Tiger".
The story ends with the death of Fokir, the mourning of Piya, her departure and finally her return "home", the surprising term she used for the Indian backwaters where she had so recently been emotionally traumatized in. But in her defense, she says she came "home" because to her home was where the dolphins were. The tides had gone out, and yet there should be no surprise that they have returned.
