Lucy Westenra and Detective Grant eventually become lovers and this complicates the lives of the police officer and the beautiful female vampire as later circumstances seem to implicate everyone's hidden agenda, betrayal, and deception.
The virus creator, Dr. Fleming, doesn't seem to need all that much coercion to make a human biological weapon, as he wanted immortality and the Elder vampire was all too happy to manipulate him.
Only due to the trust between the human police officers and their vampire allies is the deadly virus plot brought to an end.
The subplot of the vampire renegade leader and the overly zealous government agent Seward were also resolved without a bloody war.
Human Detective Grant and Vampire Officer Grey become permanent police partners at the end of the movie.