Chances are you have seen Ken Russell's film of this which is pretty dire, but has become a cult movie. Our story opens here in 1860 when Richard Salton writes to his grand-nephew, Adam Salton, who resides in Australia.
Adam comes to England to visit Richard, and they both, with Richard's friend Sir Nathaniel becomes firm friends. Soon Adam meets Edgar Caswall who is a local heir, and the very sexy Lady Arabella, who obviously is after getting her hands on Caswall's money. As Lady Arabella seems more than she appears, and strange things start happening, Caswall appears to go mad. Sir Nathaniel is a sort of Van Helsing type, and with him on the case things are bound to come to a head.
This is overtly more sexual than Dracula and is probably Stoker's most read tale after Dracula. It is probable that this was inspired by a legend, most people pointing to 'The Worm of Lambton', although similar legends pervade our landscape.