Walpurgisnacht

"Here a
thought struck me, which came under almost myssterious circumstances
and with a terrible shock. This was Walpurgis Night!

Walpurgis Night was when, according to the belief of millions of
people, the devil was abroad--when the graves were opened and the
dead came forth and walked. When all evil things of earth and air
and water held revel."

-Bram Stoker, "Dracula's Guest"