The Priest movie plays much like a graphic novel. This style makes it easy to for the suspension of disbelief. It is already fake.
Working with that, I was able to get into the movie without thinking too deeply. The vampires structure reminded me more of Aliens. There is a queen. They live in a hive. It seems that they have come from outer space, This is a departure from the traditional origins of a black-arts undead vampire. Lifeforce, a film from 1985, explored this possibility. The only thing missing is that they only feed on humans, they do not seem to need them as hosts.
Karl Urban does a great job as the black-hatted, trenchcoated, vampire/human hybrid. Karl is going to become the Science Fiction Convention favorite for the current generation.
Christopher Plummer however, will always be Captain Von Trapp from the Sound of Music and nothing else.
There is a steampunk / goth element to this. Principally, the trains. The vampires are attempting to take over by stealth, by using the trains to travel by day. The cities are obscured by smog, so the vampires will not be harmed by the sun as they attempt to destroy the humans.
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