Mike Sullivan is a rookie cop in late nineteenth-century Los Angeles. There are only seventy officers on the squad, and they still ride horses to catch criminals. As the city population reaches over one million, crime drastically increases, but Mike is a cop, ready to face any foe-at least of the human variety.
Following the mysterious deaths of two men, an old sailor named William Shakespeare O'Brien appears, claiming the deaths were the work of a female vampire who boarded his ship. Mike is skeptical, but at O'Brien's coaxing he reads Bram Stoker's Dracula and begins to wonder how much of O'Brien's story is true.
As Mike delves deeper into the murder investigation, he is distracted by his mother's serious illness and his love for Jennifer Fitzgerald, the woman he hopes to marry. There is no time for distraction, though, as Mike soon realizes O'Brien is right: a vampire hunts the streets of Los Angeles, and conventional police work will not stop this bloodthirsty murderess.