Complex sentence: Soon after Harker's arrival at the castle, he is made a prisoner by this Count Dracula, who is revealed as a vampire, and has a dangerous encounter with the seductive Brides of Dracula.
Split into simpler sentences: Soon after Harker's arrival at the castle, he is made a prisoner by this Count Dracula, who is revealed as a vampire. Harker also has a dangerous encounter with the seductive Brides of Dracula.