Jonathan Harker, an English lawyer, travels to Transylvania to help hammer out the logistical details for a wealthy nobleman, Count Dracula, who wants to purchase a house in England. Harker realizes pretty early on that something is weird about the Count. Yep, you guessed it: he's a vampire. And he's not moving to London for the museums – he wants to drink the blood of English people!
Jonathan Harker manages to escape from Castle Dracula without being killed by the vampire brides of Dracula, but he gets held up in Budapest with a bad case of vampire-induced brain fever, so he doesn't get back to England in time to warn anybody. Meanwhile, Dracula arrives in England and immediately starts sucking the blood of Lucy Westenra, the best friend of Harker's fiancée, Mina Murray.
Lucy's doctors are unable to save her from Dracula, in spite of many blood transfusions. Dracula transforms Lucy into a vampire by feeding her his blood. All of Lucy's lovers and their friends unite in a common cause: to kill vampire Lucy so that she can die a natural, peaceful death. After saving Lucy by killing her, they all agree to work together to kill Dracula himself.
Dracula attacks Mina, Jonathan Harker's wife, under the noses of the Crew of Light (the group dedicated to destroying Dracula). He forces her to drink his blood, forming a connection between them that allows him to control her – but also allows her to see into his mind. Unless Dracula is killed, Mina will eventually transform into a vampire like Lucy did.
The band of vampire fighters place Holy Communion Wafers in all of Dracula's various hideouts, rendering them useless to him. They're trying to drive him out of hiding so that they can kill him.
Dracula realizes what they're up to and tries to escape to his home. Van Helsing and the rest of the Crew of Light chase him back to Transylvania, and eventually catch up to him just before he reaches Castle Dracula.
There's a final fight in which Quincey Morris, one of the vampire fighters, gets stabbed in the side. He stays alive long enough to help kill Dracula for good, and then dies a noble death. Mina is healed, and everyone else lives happily ever after.