This Hammer film about vampires is not great, but it does have some things going for it. The story takes place in the early 1800s; a vampire’s curse affects a Serbian village, and fifteen years later, a creepy circus of vampires and their followers arrives seeking to bring back an evil Count by using the blood of young people from the village. “Vampire Circus” (made between 1971 and 1972) is a lesser-known Hamm…