Deen meets a distant relative in Kolkata who introduces him to the Bengali folk legend of the Gun Merchant.

Nilima Bose tells Deen about the shrine connected to the Gun Merchant legend and asks him to help preserve the story.

Deen receives an unexpected phone call from Cinta describing a dream about the two of them watching a jatra performance together in Calcutta.

A king cobra rears up at the shrine entrance; Tipu throws a fishing net over it to protect Deen and is bitten.

While being taken to hospital by boat, the delirious Tipu has visions and calls out the name of a dolphin named Rani.

Piya and Deen travel to Garjontola and discover that Rani and her entire pod have inexplicably beached themselves.

Tipu contacts Deen by video call and urgently insists that Deen must meet Cinta and not let anything stop him.

On a beach near Los Angeles, a yellow-bellied sea snake bites and kills Gisa's dog, a species rarely found in that area.

During Cinta's closing conference talk about Venice, Deen realizes that Gun Island from the legend is actually Venice itself.

Deen and Cinta analyze the legend's linguistic clues together and piece together the Gun Merchant's real historical journey.

Deen arrives in Venice to work on Gisa's documentary and unexpectedly runs into Rafi on his very first day there.

While visiting Rafi in hospital, Deen learns that Tipu is among the passengers on the refugee vessel called the Blue Boat.

Deen arranges for himself, Piya, Rafi, Cinta, and Gisa to join an activist vessel heading out to meet the refugee boat.

As the Blue Boat arrives, dolphins, whales, and millions of birds surround it while bioluminescence lights the water beneath.

The Italian admiral orders the refugees rescued, calling the animal gathering a miracle; Cinta passes away peacefully in her cabin.

Deen Datta, a rare books dealer visiting Kolkata, is drawn into the mystery of the Gun Merchant, a Bengali folk figure who fled overseas to escape the snake goddess Manasa Devi. A cobra attack at a Sunderbans shrine sets supernatural events in motion, including a bitten Tipu calling out the name of a dolphin moments before she inexplicably beaches herself. Months later, venomous creatures follow Deen to Los Angeles, where his historian friend Cinta's conference talk reveals that Gun Island from the legend is actually Venice. Traveling to Venice as a documentary translator, Deen unexpectedly meets Rafi and eventually learns that Tipu is among the passengers on a refugee boat approaching Italy from Egypt. Deen gathers the group and joins an activist vessel to intercept the boat, witnessing a gathering of dolphins, whales, and birds that compels the Italian navy admiral to rescue the refugees as a miracle. As the rescue succeeds, Cinta passes away peacefully in her cabin, having witnessed the sign she had waited for since her daughter Lucia's death.

The headline journey from legend to miracle.

Moyna picks Deen up before the shrine visit and describes Tipu's troubled behavior and unexplained income after his father's death.

While piloting the boat to the shrine, Horen tells Deen his own version of the Gun Merchant's legend.

Tipu reveals to Deen that he earns money by connecting people to dalals who help migrants cross borders illegally.

Deen explores the shrine's temple walls and deciphers symbolic friezes depicting recurring figures from the Gun Merchant's legend.

Delirious on the hospital boat, Tipu asks Rafi for his real name and grows calm when Rafi admits he is named Ilyas.

Doctors treat Tipu with the correct antivenins at the Lusibari hospital and he slowly begins to recover.

Back in Brooklyn, Deen begins receiving unusual chat messages from Tipu asking about ghosts, shamans, and communicating with animals.

The LA conference opens with a historian's talk connecting 17th-century climate disasters to the current global crisis and a coming apocalypse.

Piya emails Deen to report that the Gun Merchant's shrine was completely destroyed in a storm a few months earlier.

Lubna-khala takes Deen through Venice's streets and reveals how many Bangla-speaking migrants have settled throughout the city.

Rafi tells Deen that the Gun Merchant was bitten by a venomous spider inside the most secure room on Gun Island.

Deen discovers that Rafi was mugged on the orders of a scafista who wanted to keep him permanently trapped in debt.

Cinta takes Deen to the Church of the Black Madonna of Salute and points out a Latin inscription on its floor.

A wooden pier at Fondamente Nove collapses beneath Cinta and Deen when shipworms are revealed to have eaten through the beams.

Piya and Rafi spot an extraordinary number of cetacean species aboard the Lucania, all traveling in the same direction as the ship.

Before reaching the shrine, Deen learns of Tipu's troubled past and illegal migration work from his mother Moyna, and hears Horen's distinctive version of the Gun Merchant's tale on the river. At the shrine, Deen deciphers symbolic friezes on the temple walls, and on the journey back, Tipu's delirium produces the revelation that Rafi shares his name with the legendary captain Ilyas. After Tipu recovers in hospital, Deen returns to Brooklyn where Tipu's cryptic messages about ghosts and shamans begin to unsettle him further. A conference historian's talk about 17th-century climate disasters and news of the shrine's destruction frame the novel's deeper ecological themes, while in Venice, Lubna-khala reveals the city's hidden Bangladeshi migrant community and Rafi shares the missing piece of the legend involving a venomous spider. The novel's tension escalates as Rafi is mugged by a scafista's men and Cinta fractures her ankle on a rotting pier, before the Lucania's journey reveals an unprecedented gathering of cetaceans heading toward the Blue Boat.

The supporting details that deepen the legend.

Nilima reveals to Deen that the shrine is maintained by a Muslim family and revered by both Hindu and Muslim communities.

After Cinta's phone call, Deen checks his journal and realizes the jatra they once watched together featured the legend of Manasa Devi.

Rafi reveals that a cobra has lived near the shrine for years and had its hood raised directly behind Deen moments earlier.

After discovering Rani's pod beached, Piya dismisses Tipu's apparent vision and insists the dolphins fled because of the refinery's pollution.

Piya tells Deen that Tipu has been suffering recurring blackouts and migraines since the snakebite, relieved only by spending time with Rafi.

On a flight to LA, Deen accidentally broadcasts Urdu music and later screams at a hawk carrying a snake, triggering his detention.

Cinta suggests to Deen that the Gun Merchant's story was never written down because it has not yet come to an end.

After the dog's death, Gisa tells Cinta and Deen she heard Lucia's voice calling out as the sea snake struck the dog.

Piya contacts Deen in Venice to reveal that Tipu sent an email predicting the dolphin beaching and has not been in Bangalore.

Bilal tells Deen how he was separated from his friend Kabir during migration, explaining why he fully understands Rafi's sacrifice for Tipu.

Deen becomes entranced in a Venice library and attempts to open a rare book's display case before being stopped by security.

At the Venice hospital, Rafi tells Deen that Tipu followed a vision of an Ethiopian woman from Turkey all the way to Egypt.

A bearded man in a yellow robe appears during the storm and directs the group's storm-blocked bus toward an alternate route.

On the Lucania, Piya tells Deen she has felt guilty ever since Tipu's father, Fokir, died protecting her during a cyclone.

Cinta tells Deen that Lucia has come to take her away and thanks him warmly for the gift he has given her.

From the outset, key revelations reshape Deen's understanding of the legend and the people around him, beginning with the shrine's interfaith appeal and the realization that Cinta's dream was about a performance of the Manasa Devi legend. Rafi's disclosure about the cobra at the shrine and Piya's stubborn rejection of Tipu's visions establish the novel's central tension between supernatural and rational explanations. As Deen travels to Los Angeles and later Venice, charged moments accumulate—from being detained on a plane to hearing Gisa report Lucia's voice at her dog's death—blurring the line between coincidence and destiny. In Venice, critical discoveries mount as Tipu is revealed to have left India and followed a prophetic dream of an Ethiopian woman all the way to Egypt and onto the Blue Boat. The climax is shaped by intimate human moments—Bilal's story of migration loss, Piya's confession of guilt over Fokir's death, and an uncanny encounter with a stranger in a yellow robe—before Cinta's farewell to Deen brings the novel's emotional arc to its close.