Arent is a physically imposing military veteran who works as a bodyguard for the famous investigator Sammy Pipps. He bears multiple battle scars across his back, neck, and chin, and is missing a piece of his right ear. Though born into one of the wealthiest families in the Provinces, Arent actively rejects his noble heritage to pursue a life of honor instead of profit. With his employer locked in a tiny cell on the Saardam, Arent reluctantly takes over the investigation into the demonic signs appearing on the ship.

Sara is a noblewoman and the wife of Governor General Jan Haan. Trapped in a highly abusive marriage arranged solely for wealth and status, she longs for freedom for herself and her daughter. She is a skilled healer who learned the craft from her mother. As the voyage progresses, she quietly rebels against aristocratic expectations, trading her heavy brocade gowns for practical clothing so she can investigate the ship's mysteries alongside Arent.

Sammy is a famously successful detective who travels the Provinces solving complex crimes for wealthy clients. He is physically slight, featuring dark curls and high cheekbones. Governor General Jan Haan imprisons him in a tiny, dark, foul-smelling cell at the bow of the Saardam for the duration of the voyage. Despite deteriorating physical health in captivity, he meets with Arent at midnight to offer deductive insights into the ship's unfolding horrors.

Creesjie is a wealthy noblewoman traveling as a passenger aboard the Saardam. She serves as the mistress to Jan Haan and views the restrictions of 17th-century nobility as a practical trade-off for physical safety and financial security. She confidently navigates the social hierarchy of the ship and assists her friend Sara in attempting to uncover the source of the demonic threats.

Jan Haan is the Governor General of the United East India Company outpost in Batavia. He is a physically unattractive, ruthlessly ambitious man who prioritizes corporate profits and his own career advancement over human life. He seeks a seat among the powerful Gentlemen 17 upon his return to Amsterdam. He rules his family through emotional and physical violence and demands strict compliance from his crew.

Old Tom is a legendary demonic entity believed to be stalking the passengers of the Saardam. According to the witchfinders' daemonologica, the demon performs unholy miracles to prove its power before offering dark bargains, whispering promises of immense wealth and fortune to those willing to commit acts of evil.

Lia is the intelligent, observant young daughter of Sara and Jan Haan. She possesses a natural talent for engineering and structural design, though her mother frequently cautions her to hide this intellect to avoid offending the men around them. She actively contributes to the investigation by constructing a detailed physical model of the Saardam to locate secret compartments.

Sander is a frail priest and the last living witchfinder in the Provinces. He boards the Saardam after receiving a mysterious summons, bringing with him a heavy daemonologica that contains drawings and notes on demonic entities. He holds sermons for the crew and provides the passengers with crucial information regarding the demon known as Old Tom.

Isabel is a young, lowborn woman who acts as a ward and assistant to Sander Kers. Having grown up in extreme poverty, she decides to brave the dangers of the sea voyage rather than return to a life of destitution in Batavia. She assists Kers with his rituals and helps the noblewomen research the entries in the daemonologica.

Drecht is the Guard Captain of the mercenaries hired to protect Jan Haan and his family. He is a pragmatic, cynical military man who believes human beings are perfectly capable of committing atrocities without the influence of supernatural demons. He drinks and sings with Arent on the deck but remains strictly obedient to his employment contracts.

Vos is the intensely loyal chamberlain to Jan Haan. He operates like a machine composed of cogs and springs, handling all logistical details for the Governor General with emotionless efficiency. He secretly observes Creesjie Jens and harbors his own ambitions of gaining vast wealth to rise above his servant status.

Wyck is the brutal boatswain of the Saardam. He enforces total obedience among the crew through intimidation and physical beatings. He deeply resents the wealthy passengers aboard the ship and actively prevents the sailors from answering Arent's questions regarding the voyage's mysteries.

Bosey is a bow-legged ship carpenter afflicted with Hansen's disease. Before the voyage begins, he delivers an impossible warning to the travelers, speaking clearly despite having previously had his tongue removed by the boatswain. His fiery end sets the supernatural mystery in motion.

Crauwels is the handsome, well-dressed captain of the Saardam. Unlike the corporate merchants on board, he cares deeply about the physical safety of his ship and crew. He frequently clashes with Jan Haan and the chief merchant over the dangerous decisions made in the name of company profit.

Van Schooten is the chief merchant and master of the voyage. He serves as the primary representative of the United East India Company aboard the Saardam, holding legal authority over the captain. He drinks heavily and insists on strictly enforcing company debt policies, focusing entirely on delivering the ship's cargo for maximum profit.

Larme is the first mate of the Saardam. He views the ship as his true home and remains fiercely loyal to his fellow sailors. He is highly protective of the crew's secrets and acts brusque and dismissive when Arent attempts to question him about Bosey's past.

Henri is a carpenter's mate aboard the Saardam. He is terrified of the boatswain, Johannes Wyck, but provides Sara with early, crucial details about Bosey's mutilation in exchange for coin.

Dorothea is Sara Wessel's loyal maid. She embodies the strict standards of 17th-century aristocratic service, highly concerned with appearances, nobility, and protocol. She frequently scolds men who fail to show Sara the proper respect due to a lady of her station.

Eggert is one of the musketeers assigned to guard Sammy Pipps. He is aggressive and quick to escalate physical confrontations, drawing a dagger against Arent during a struggle outside Sammy's cell on the first day of the voyage.

Thyman is a rough musketeer tasked with guarding Sammy Pipps alongside Eggert. He causes internal friction among the guards by cheating at dice, a fact that Sammy uses to deescalate a violent standoff on the deck.