Weller Roy Kinnear is travelling through Eastern Europe when a tense struggle knocks him from his carriage, leaving him unconscious as night falls. When he awakens, a caped figure screams in agony, impaled by a large crucifix through the back. The man dies and disintegrates into dust. Among the remnants—a ring, a cape with its clasp, and dried blood—Weller finds a brooch marked with the name Dracula Christopher Lee.
Some time later, three gentlemen—William Hargood [Geoffrey Keen], Samuel Paxton [Peter Sallis], and Jonathon Secker [John Carson]—form a circle that outwardly champions charity, but in private they visit brothels. One night, they are drawn to a young man who bursts into the brothel and is tended to after snapping his fingers. The man is Lord Courtley [Ralph Bates], who was disinherited years ago for celebrating a Black Mass. Courtley leads them to the Cafe Royal and promises experiences they will never forget if they visit Weller and purchase from him Dracula's ring, cloak, and dried blood.
Back at an abandoned church, a ceremony unfolds in which Courtley mixes the blood with his own and urges the others to drink. They refuse; Courtley drinks the concoction himself, screams, and collapses. As he dies, his body seems to dissolve, and Dracula rises, swearing that his killers will be destroyed.
Meanwhile, William Hargood, a heavy drinker, mistreats his daughter Alice [Linda Hayden], who continues to see Paul Paxton [Anthony Higgins], the son of Samuel Paxton. Dracula hypnotizes Alice, compelling her to take up a shovel and kill her father. The next day, Hargood is found dead and Alice is missing. At Hargood’s funeral, his daughter’s absence draws the attention of Paul’s sister Lucy [Isla Blair]. That night, the two sisters enter the church, and Alice introduces Lucy to a dark figure. Believing him to be Alice’s lover, Lucy is confronted by Dracula, who turns her into a vampire.
With Hargood dead and Alice and Lucy missing, Paxton teams with Secker to search the church. Courtley’s body has vanished, but they discover Lucy asleep in a coffin with marks on her throat. Realizing she is a vampire, Secker tries to stake her, but Paxton shoots Secker in the arm, forcing him to flee, and weeps over the body. That same night, Secker’s son Jeremy Secker [Martin Jarvis] sees Lucy, his fiancée, and approaches her. She bites his throat, enslaving him while Dracula watches. The newly turned Jeremy stabs his father to death on Lucy’s orders. When she pleads for his approval, Dracula drains Lucy dry and leaves her destroyed.
Back at the church, Dracula plans to bite Alice again, but a rooster crows, and he retreats to his coffin, retreating from the sanctified space.
Secker’s death leaves Jeremy’s future precarious as his late father’s body is used as evidence. Paul finds a letter in which Secker instructs him on how to fight the vampires. He then returns to the church, discovering Lucy’s exsanguinated body floating in a lake. Paul bars the door with a cross and clears the altar of Black Mass instruments, replacing them with the proper items. He calls for Alice, who appears with Dracula.
Paul confronts Dracula with a cross, but Alice, still under the vampire’s thrall, disarms him. Dracula dismisses her and attempts to leave, yet the barred door keeps him in. He hurls objects from the balcony as he backs toward a stained-glass window depicting a cross. The window shatters, and the recited Lord’s Prayer in Latin echoes through the transformed space. The power of the re-sanctified church overwhelms Dracula, who collapses onto the altar and dissolves to dust. With the vampire destroyed, Paul and Alice walk away, the dawn of a hard-won peace washing over the church.