On August 6, 1897, the merchant vessel Demeter mysteriously arrives at the English shore, leaving behind a trail of destruction. Among the remnants discovered by the police lies the captain's log authored by Captain Eliot.
Just a month prior, the Demeter docked in Varna, Bulgaria, to gather cargo bound for London. The shipment comprised numerous large wooden crates, transported by locals from Romania. Strangely, the local workers adamantly refuse to load the crates, expressing a need to vacate the area before nightfall. One local pays the quartermaster, Wojchek, and crewman Olgaren a sizable sum, wishing them a safe journey before exiting the scene.
Meanwhile, a skilled doctor named Clemens, educated at Cambridge University, overhears the crew's search for men and attempts to pitch his expertise in medicine and astronomy as a valuable addition to the team. Wojchek, however, chooses an older man instead. Yet, fate smiles upon Clemens when, while helping to load a crate, the older recruit panics upon spotting a dragon emblem and inadvertently lets go of the tackle rope, nearly crushing Eliot's grandson, Toby. Clemens steps in heroically to save Toby, leading Eliot to hire Clemens in gratitude.
The plot thickens when one of the crates bursts open in the cargo hold, revealing a woman entombed in dirt. With barely a pulse, Clemens spring into action, performing blood transfusions to save her from what he suspects is an infection. As they sail the Aegean Sea, Clemens and Olgaren glimpse a shadowy figure haunting the fog-laden deck.
Dread descends upon the crew when every animal onboard meets a grisly fate, including the beloved ship's dog, Huckleberry. Fearing rabies, the crew tosses the remains overboard. In this dire moment, Anna, a clandestine stowaway, awakens and warns them of a monster from Transylvania—a beast that preys on human blood. Known as Dracula, she confides that she was once a blood slave, a sacrifice to keep the creature at bay. With multiple bite marks adorning her body, she insists that Dracula lurks among them.
As the night wears on, Dracula begins his hunt, converting Olgaren into one of his vampiric thralls. In a terrifying sequence, Olgaren breaks free from his restraints and seeks out Toby, cornering him in the captain's quarters. In a desperate bid to save the boy, the crew intervenes, but the horror escalates when Toby himself gets bitten. Alas, morning arrives, and the once human Olgaren disintegrates in the sunlight, providing a grim reminder of Dracula's curse. Despite Toby's grandfather's desperate attempts to save him through blood transfusions, the boy succumbs to the vampiric embrace.
With dwindling options, the surviving crew resolve to destroy the ship, intending to prevent Dracula from sowing further chaos upon their arrival in London. Yet, in a tragic turn, both Captain Eliot, Abrams, and Wojchek fall prey to Dracula's wrath, while Anna suffers a bite during a heroic attempt to save Clemens. A fierce confrontation ensues as Clemens swings an axe at Dracula, enabling Anna to smite the creature using a shattered mast. Believing they have triumphed, the duo leaps overboard, unaware that Dracula is still breathing, ready to unleash new horrors.
Anna and Clemens manage to find refuge on flotsam, but her revelation of vampirism bears heavy on their hearts; despite Clemens' blood transfusions delaying the inevitable, transformation is unavoidable. As dawn approaches, in a heart-wrenching decision to escape monstrosity, Anna chooses to self-immolate in the rising sun while Clemens floats to shore.
Arriving in London, Clemens gathers his thoughts in a local tavern, sketching Anna’s likeness in his notebook. Suddenly, the familiar tapping signal from the Demeter's crew of "all clear" reaches his ears, only for him to spot Dracula, now disguised as an aristocrat, taunting him from the shadows. With determination ignited, Clemens departs the pub, resolute in his vow to avenge his fallen comrades by sending Dracula back to the depths of Hell.
