What happens to Hugo Baskerville at the end of the legend? What is so special about the hound?

The legend goes that in the 1640's an evil guy named Hugo Baskerville had kidnapped a young woman and locked her in his castle. She escapes and Hugo goes after her. The girl dies of exhaustion and Hugo is found being eaten by a supposed "demon hound" which apparently haunts the Baskerville family to this day.