1810 England, the height of the Napoleonic wars. It was thought that humans walked the path of enlightenment leaving monsters and dark things behind. However, those monsters and night stalkers merely hide in the darkness, as a young maid, Bernadette, soon finds out.
Vampires drink blood the same way you or I drink any potable liquid. Their fangs are sharp so they can penetrate the skin. Their fangs do have a hole in them which, under certain circumstances, will 'leak' their blood. This is how their blood gets into the victim's blood stream, infecting them with vampirism.