Lucy Westenra is a vivacious young woman who is much praised for her beauty, purity and sweet nature. These qualities earn her three suitors, all of whom propose to her on the same day: Arthur Holmwood, the wealthy son of Lord Godalming; Quincey Morris, an American cowboy; and Doctor John Seward, an asylum psychiatrist.
Lucy accepts Arthur's proposal, but soon begins suffering from severe anaemia. She has, in fact, become the victim of Count Dracula, who is slowly draining her of blood. Despite the best efforts of Dr. Seward and Dr. Abraham Van Helsing, Lucy's condition rapidly deteriorates. Dr. Van Helsing correctly identifies the true cause of her illness, and puts up garlic around her sickbed to repel Dracula. Even after four blood transfusions (from Holmwood, Seward, Van Helsing, and Morris, respectively) and although the doctors try to keep a constant vigil over her condition, their efforts prove futile. Lucy and her mother are together when a wolf - either controlled by Dracula or Dracula himself - comes crashing through the window while the two women are left unattended. The mother dies from a heart attack, while Dracula drains Lucy to the point of near death.
The men find her the next morning barely alive; they try a transfusion, but by this point it's much too late, as the bite marks on her throat have vanished and her teeth now sport longer canines. For a moment, when Arthur is near her, she requests a kiss, while turning much more voluptuous. Helsing pulls Arthur away, knowing that it is the monster talking, and not Lucy. Lucy, reverting back to normal and also realizing she's becoming inhuman, asks Van Helsing to protect Arthur. Helsing swears to do so for Lucy's sake. Lucy soon dies from her blood loss. The men think it's over, but Helsing knows that with Lucy's death, her transformation into the undead is just beginning.
Sure enough, after her death reports of children being attacked at night are heard, with each child claiming it was the "Bloofer Lady" (child speak for "Beautiful Lady"). The children also have bite marks on their throats, though none of their blood has been seriously drained. Dr Van Helsing realizes that Lucy has now risen as a vampire, and asks Dr Seward, Arthur, and Quincey to help him destroy the undead creature. When they doubt him, Helsing leads Seward with him at first to show him first-hand - first by showing that Lucy's coffin is empty, and then waiting when she comes with another child to feed on. She once again only takes a little blood before leaving the child and heading back to her crypt. Van Helsing and Seward make sure the child is all right and go into the crypt where the coffin now contains Lucy's body. However, as Helsing points out, Lucy's body hasn't decayed a day since her death, as the undead never age.
That next night, Van Helsing gathers the rest of the men and puts a plaster made from consecrated hosts over Lucy's crypt while she's out feeding. The men wait for her to come back where they see the monstrous form she's now become. They confront her, stopping her from biting her current victim. Upon seeing Arthur, Lucy changes her tone and stance to a more sweet nature, beckoning him to come to her so they can be undead together. Her hypnotic spell almost works until Van Helsing flashes a cross at her, repelling her. She flees to her crypt, but is unable to enter until Van Helsing removes some of the plaster. Even with the small space, the men are astonished as Lucy uses her powers to slip inside as if it was nothing. The men soon follow and find Lucy in her coffin, resting. Van Helsing explains to the others that the Lucy they know is indeed dead, but has been resurrected in a corrupted form that must feed on blood, the result of vampirism if a victim has been fully drained. He warns that she is a newly made bride now under Dracula's command and, unless she is stopped, will continue her nightly feedings to the point of fully draining her victims, and will have no qualms about turning friends or family into vampires either.
Van Helsing feels it best that the men who loved Lucy in life play a role in freeing her soul. On his instructions, they stake and decapitate Lucy, destroying only the vampire part of her, and Lucy's corpse is finally able to rest in peace while her spirit enters the kingdom of Heaven.