Dracula by Gary Wright

Jonathan Harker's employer sends him to do business with a mysterious foreign nobleman, Dracula. Before long, Harker realizes that he is not a guest, but a prisoner in Dracula's castle. Harker barely escapes the castle with his life, and returns home to England, only to find that Dracula has gotten there first, and is already preying on people close to Harker - including his wife, Mina. Armed with this knowledge, the small band of friends tracks down their evil adversary to his London lair, for a final do-or-die confrontation.