In 1900 Travancore, a twelve-year-old bride leaves her widowed mother for an arranged marriage to an older widower. Taken to Parambil—five hundred acres of mostly wild land curiously set back from water—she learns its rhythms with the help of her sister-in-law Thankamma and the loyal foreman, Shamuel. A rescued elephant, Damodaran, roams in and out, emblem of the estate’s improbable bonds. The young wife, soon called Ammachi and later Big Ammachi, slowly claims her place, then in a watershed moment confesses her loneliness and wins from her husband an overland path to church. Intimacy follows, and with it belonging.

Her family takes shape around JoJo, her husband’s son, and later a daughter the household calls Baby Mol. The monsoon reveals a quirk shared by father and son: a visceral aversion to water. The joy of harvests and kitchen mastery cannot protect them from tragedy; after rains, JoJo slips into a ditch and drowns. In the aftermath, her husband unveils a hidden family genealogy—a Water Tree—marked across generations by drownings. Big Ammachi, discovering his illiteracy and partial deafness, takes stewardship of the record and names the affliction “the Condition,” praying that God will send someone to explain or cure it.

Parallel to Parambil, Digby Kilgour grows up in Glasgow, loses his mother to suicide, and sails to India for surgical training in 1933. In Madras he meets Matron Honorine, whose fierce competence saves him during his first operation, and Dr. V. V. Ravichandran, whose brilliance models judgment anchored in context. Digby’s gifts bloom as he repairs ulcer-ravaged stomachs and massive hydroceles in the segregated native wards, while his corrupt superior, Claude Arnold, drinks and deflects responsibility. When Claude fatally incises a carotid aneurysm on the charismatic Jeb Tuttleberry, public outrage forces an inquiry. Claude schemes to smear Digby through a bogus adultery case naming Claude’s wife, Celeste; Digby and Celeste fall into a doomed affair, and she dies in a studio fire. Burned and broken, Digby flees to the Western Ghats, where Franz and Lena Mylin shelter him.

There, Swedish surgeon Rune Orqvist finds Digby and, invoking indigenous reconstructive methods, restores his hands at Saint Bridget’s Leprosarium. Rune’s vocation sprang from a mystical encounter with a blind leper; he has rebuilt an abandoned lazaretto into a refuge where prevention and dignity matter as much as surgery. Under Rune’s tutelage—and after Rune’s sudden death—Digby steadies the institution, then watches Swedish nuns assume the work. He remains in Kerala, his purpose transformed by service and loss.

Back at Parambil, Big Ammachi bears a son, Philipose; her husband declines with headaches and stroke-like changes and dies at home. Fearing the river’s pull on her water-drawn child, Big Ammachi leads Philipose to a saint’s tomb and binds him to a vow never to swim alone. She opens a school that exposes caste cruelty when the kaniyan teacher beats Joppan, Shamuel’s gifted son; Ammachi quietly tutors the boy while awaiting a truly open school. Philipose grows into a restless walker, invents an iridescent ink, and studies English with the erudite, tipsy Koshy Saar. During a flood, he saves a choking infant and, breaking his vow, launches a dugout through raging water to reach help at Saint Bridget’s—the first, fleeting crossing of paths with Digby’s world.

Philipose and Elsie Thetanatt marry. Art flourishes: Elsie’s studio produces portraits that change lives, yet domestic fissures open around a jackfruit tree that blocks her light and Philipose’s reluctance to cut it. Their son, Ninan, is born extremely premature and survives through vigilant skin-to-skin care; like the men in the Water Tree, he is enthralled and imperiled by water. After independence, Elsie’s work wins Madras’s top prize, but typhoid and the unresolved tree quarrel strain the marriage. Philipose finally has the tree lopped; in the first lull of the monsoon, Ninan climbs the spiked remnant and is fatally impaled. Grief hardens into blame. Elsie departs; soon after, her father dies. At Parambil, Baby Mol falters and Philipose slides into opium. Months later Elsie returns briefly to comfort Baby Mol, then, as the floods peak, vanishes; her neatly folded clothes by the river suggest a drowning. Big Ammachi, finding a sketch of a mother and child in Elsie’s secret “nest,” reads it as a charge to raise little Mariamma, the daughter Elsie recently bore and left in her care.

Elsewhere, Digby’s planter-physician life continues; he saves a woman, Lizzi, after an assault by her atropine-delirious husband, and later their son, Lenin Evermore, becomes a recurring presence in Parambil’s future. In 1959 smallpox devastates Lenin’s family; orphaned and shunned, he is aided by a pulayi woman and a priest. Meanwhile, Big Ammachi’s village uplift gathers force under a dynamic couple known as Uplift Master and Shoshamma; petitions, latrines, and literacy schemes culminate in a maharajah’s visit and a new post office. At the Maramon Convention, Uplift Master translates an American preacher’s fervor into a mandate for a world-class hospital; Big Ammachi’s public donation of her gold triggers a cascade of gifts and a Hospital Fund. She urges Mariamma to make knowledge her antidote to fear.

Age gathers its due. Baby Mol and Big Ammachi die peacefully, entwined, as Parambil stands on the threshold of its hospital. Mariamma, now in medical school, lives by the motto “The Dead shall inform the Living,” excelling at anatomy and embryology. She survives an examiner’s assault by fighting back, and she falls in love with Lenin, now a fugitive drawn to armed struggle after witnessing state-backed dispossession. They separate over irreconcilable callings—he to the forest, she to healing. Mentored by pathologist Dr. Uma Ramasamy, Mariamma dissects leprosy-affected nerves and hones a rare 3‑D visual skill. When a train disaster claims Philipose, Mariamma persuades Uma to perform an unusually complete autopsy; later, microscopic examination reveals tiny bilateral acoustic neuromas. With the Water Tree genealogy beside the brain, Uma and a neurologist explain how a variant of neurofibromatosis, by eroding balance and hearing, likely doomed relatives in water. Mariamma fuses grief to purpose: she will become a neurosurgeon and return to build the hospital her grandmother envisioned.

Back in Parambil, Mariamma opens the mission hospital’s casualty and outpatient services by stealth and persuasion, operating in emergencies with Joppan and watchman Raghavan at her side. A newspaper feature about the Condition prompts other families with similar histories to come forward, expanding her map of inheritance. Then an urgent note arrives: Lenin has reached Saint Bridget’s comatose, asking for her. Diagnosing obstructive hydrocephalus from an acoustic neuroma, Mariamma performs a blind ventricular tap and revives him, then rushes him to Vellore, where a near‑total tumor removal succeeds. Police take custody; press coverage recasts him as the “Naxalite Priest,” tempering danger without erasing it.

Shattered by a revelation in Philipose’s journals—that Elsie returned after a year away already pregnant—Mariamma confronts her identity and follows the trail to Saint Bridget’s. There, after watching Digby restore hand function to a leprosy patient, she learns the unspoken truth: her mother, Elsie, is alive at the leprosarium, disfigured and blind from leprosy; Digby, who saved and loved her, remained to serve in silence. Elsie’s choice to vanish—made in the face of disease, stigma, and a newborn’s vulnerability—kept mother and daughter apart for decades. Through glass, Mariamma places her palms over Elsie’s, bridging secrecy and time. The covenant that began in water resolves into a different promise: to turn inheritance into knowledge, loss into institutions of care, and private sorrow into a public cure.