The Devil and the Dark Water by Stuart Turton, published in 2020, is a work of historical fiction with elements of horror, detective fiction, and mystery. It follows the journey of an East India Trading Company ship, the Saardam, in 1634 as it makes its journey from a trading post in Batavia—present-day Indonesia—back to Amsterdam. The ship is stalked by what the passengers believe is a demon named Old Tom, as their livestock is slaughtered and several murders take place. While famous detective Sammy Pipps is locked up for an unknown crime, his bodyguard, Arent Hayes, must work with noblewoman Sara Wessel, her friend Creesjie, and her daughter Lia to try to solve the mystery.

Turton is the author of three novels – The Devil and the Dark Water, The 7 1/2 Deaths of Evelyn Hardcastle (2018), and The Last Murder at the End of the World (2024)—all of which contain supernatural elements. He is known for his genre-bending writing, which weaves together elements of multiple classic genres. In The Devil and the Dark Water, he does so by using a historical setting and a classic detective story, then incorporating elements of the supernatural and horror to explore themes of The Blurred Line Between Good and Evil, Corporate Power as an Engine of Corruption, and Gender and Class Inequality.

This guide uses the paperback version of the novel published by Sourcebooks Landmark in 2020.

Content Warning: This guide contains discussions of emotional and physical domestic abuse as depicted in the novel. One character is identified as having Hansen’s disease, the illness formerly known as leprosy. The source text uses a derogatory term to link this character’s identity with his illness, as was common in the era. This guide will identify him by his name (Bosey) or as “the man with leprosy” (using the historically accurate term for the illness).

Plot Summary

In 1634, several characters in the East India Trading Company outpost of Batavia, in present-day Indonesia, are readying to board the Saardam, a ship bound for Amsterdam. Arent Hayes transports Sammy Pipps, a famous investigator who has been arrested without knowing the crime. Also in the group are Governor General Jan Haan, who had Sammy arrested; Haan’s wife, Sara, and daughter, Lia Jan; their household guard; and dozens of other nobles, mercenaries, and peasants. They are stopped short in the shipyard as they see a man with leprosy mount a box of crates, warning the group that his master intends to wreak havoc on the Saardam. The man then catches fire.

After Arent ends the man’s suffering with Sara’s help, Sammy informs them both that they need to take his warning seriously. The man had no tongue yet was able to yell to the group, and he had an injured leg yet was able to climb the crates. As the Saardam sets sail, Sara does her best to convince her husband to turn back, yet Haan dismisses her. Even Arent, whose grandfather is one of Haan’s closest friends, is unable to stop the voyage. As the ship begins its journey, its sails are unfurled, revealing a symbol belonging to Old Tom, a demon who has been possessing nobles for over 30 years.

As Arent contemplates the symbol, his past is revealed. When he was a boy, a mysterious mark on his wrist led people to blame him for his father’s disappearance. To avoid the town’s criticism, Arent began painting the mark on those who tormented him, leading people to believe the mark was a sign of ill fortune. After the town killed a man named Old Tom, believing he was possessed by a demon, Arent was sent to live with his grandfather and Haan.

Armed with this new information, Sara and Arent—with the help of Lia and their friend, Creesjie—search the boat for information about the man with leprosy and Old Tom. They discover that the man’s name was Bosey, and he had his tongue cut out by the boatswain, Wyck, for repeating the word “Laxagarr” and talking about a deal he made with someone. Arent brings Sammy to the deck each day at midnight to discuss the case. The first night, Sammy points out that only seven ships left the port, but there is now an eighth lantern at sea.

Sara talks with Sander Kers, a priest on the ship who is a witchfinder, about Old Tom. The demon can be summoned by someone in need, but once it is free, it recruits more people to do its bidding. After performing three unholy miracles to recruit followers, it kills anyone who refuses it. Later that day, she overhears her husband talking with Cornelius Vos, his chamberlain, about how they summoned Old Tom 30 years ago and now fear its return.

Over the next several days, Old Tom stalks the passengers on the ship. When the Eighth Lantern appears, their livestock are slaughtered, leading to dwindling rations. Bosey is seen aboard the ship despite his presumed death, and he leads Arent and Sara to an altar to Old Tom—one that reappears each time it is taken down. While the group tries to find more information, Kers goes missing. At night, Old Tom whispers to everyone on board, promising them fortune if they agree to kill Haan.

A storm ravages the ship for two weeks, killing many and leading to discontent among the crew. After the storm passes, the captain and Haan agree to use the Folly—a navigational device that is being transported to the East India Company. However, the Folly is missing, sending Haan into a rage. He flogs the constable who was supposed to guard it and threatens more of the crew.

Arent decides to follow Vos, who leads him to crates in the hold below the ship before knocking him unconscious and tying him up. When Arent recovers, Vos admits to stealing crates full of valuables but not the Folly. As he speaks, Bosey comes up from behind and kills him but spares Arent. Meanwhile, Sara, Lia, Creesjie, and Isabel, Kers’s ward, find a list of names in Haan’s cabin. Isabel recognizes the names as families that were previously possessed by Old Tom and left dead or in ruin. When Arent arrives with the sack of valuables from Vos, Sara recognizes some of them as belonging to one of the noble houses on Haan’s list.

Arent collapses from exhaustion. Over the next three days, he lies in the sick bed. The women attempt to continue the investigation but have no further leads, while the crew continues to join with Old Tom. At dinner one evening, the Eighth Lantern burns brighter than it ever has before. As the crew readies to fight the lantern, a dense fog overtakes the ship. Bosey takes advantage of the fog to kill Wyck. After the fog leaves, Creesjie goes to Haan’s cabin to find him dead.

Arent, recovered, joins Creesjie, Sara, and Lia to investigate the cabin. Haan was comparing his list of names to the passenger manifest, and Lia discovers that one of the names—Haviland—matches one of the names on the manifest, Dalvhain. They quickly go to Dalvhain’s cabin, which is empty except for a book. In it, pictures depict the history of Old Tom and the events on the ship. The final picture shows the Saardam wrecked and Old Tom carrying survivors to an island. On deck, a mutiny breaks out, led by the captain, who has become convinced that they need to turn the ship over to Old Tom. He is slain by Jacobi Drecht, the captain of the mercenaries, and the mercenaries shoot many of the sailors. As Arent tries to stop them, he is thrown overboard.

Arent wakes up on an island and sees the Saardam run aground and destroyed. He finds Sara, Lia, Creesjie, and Isabel, who are well. Sammy is missing an eye but alive. Arent talks with Drecht, who has become the leader of the people on the beach. Drecht informs him of his plan to do anything he can to keep the mercenaries happy—including allowing them to rape the female passengers. Distraught, Arent makes a plan with Sara and the others to free as many passengers as they can. He searches the surrounding forest for an escape route and comes across a collection of cabins stocked with supplies. As he examines the area, he comes across a sword that reminds him of the dagger used to kill Haan, which makes him rethink his murder.

On the shore, Sara watches as mercenaries bring loads of valuables from the ship. She examines some, seeing that they belong to several noble families—all of whose names appeared on Haan’s list. Just as she thinks she has figured out who is behind Old Tom, Arent comes out of the forest and exclaims that he has figured out Haan’s murder. They go together to the ship and revisit each of the events. They discover that someone killed Haan from the cabin above using a long blade smuggled on board in Dalhvain’s cabin. They also deduce that the captain must have been involved as well as others.

Back at camp, Sara and Arent set a plan in motion. They send Sammy with two mercenaries out to sea on a rescue boat, then recruit Isabel to give all the survivors a sleeping draught. When they wake up, they are tied to the wreckage, and Isabel stands over them and threatens to burn them all to cleanse them of Old Tom. Their plan works, as it sends Creesjie into a panic, and she admits to the group that she was responsible for the events on the ship. Meanwhile, the rescue boat has reached a ship in the bay—the only surviving ship from the Saardam’s envoy—which was pretending to be an eighth lantern.

Lia, Sara, Arent, and Creesjie—who has revealed herself as part of the noble Haviland family—take a rowboat out to the ship. On board, they reveal the last piece of the puzzle: Sammy was working with Creesjie and is actually her brother. While Sara and Arent are upset by the betrayal, they try to explain their actions as necessary revenge for what Haan did to their families. They explain that they have been planning the voyage for years to make him truly fear Old Tom before killing him. They regret the wreck, which was never planned but was the fault of the captain who betrayed them.

In the great cabin on the ship, the five of them meet in private. Creesjie and Sammy offer to let Sara, Lia, and Arent take part of the treasure and start a new life, or to let them remain on the island, but they wish to keep Old Tom a secret. While Arent is angry and Sara contemplates their choices, she suggests a third option: the five of them continue doing Old Tom’s work. She proposes that they use the myth to take down powerful, corrupt people, and the others agree.