A Night AT Gustilobone Castle

Is Castle Gustilobone haunted or not? Does Kendall find out when he accepts a dare to spend the night there?

Sample excerpt:

“A bang… and then a bump against the door that was the north door on the east wall. I awoke with a jump only to see a man and woman standing at the foot of my sleeping bag, staring at me. I blinked and they were gone.”