Aubrey, an English gentleman, meets a mysterious man named Lord Ruthven. Aubrey goes to Rome with Ruthven but when he finds Ruthven doing wrongful acts with the daughter of a mutual acquaintance, he leaves him.

Aubrey is attracted to Lanthe, a pretty woman he meets in Greece. Lanthe shares the stories about the legends of the Vampire. Ruthven hears them talking and a couple of days later, Lanthe is found dead. Apparently, she is killed by a vampire.

Aubrey continues traveling with Ruthven. On their journey, they are attacked by bandits and Ruthven is gravely wounded. Ruthven takes a promise from Aubrey before dying, that he will not mention about this death to anyone for one year and a day.

One day, Aubrey suddenly realizes that everyone who met Ruthven suffered horribly. He is in London now and is shocked to see Ruthven alive and healthy. Ruthven starts seeing Aubrey’s sister and proposes her for marriage. Aubrey wants to warn his sister about Ruthven but Ruthven reminds him of the oath.

Aubrey is bound by the oath and has a nervous breakdown. Still he writes a letter to his sister, but she gets married to Ruthven before the letter arrives. On the night of the wedding, Aubrey’s sister is discovered dead, fully drained of her blood. Ruthven has fled.