The Flying Flagon/The Amphibious Mr. Toad/The Haunted Castle

"The Haunted Castle" Tobias the Dragon is asked by a king to scare some ghosts out of a castle where the king wants to stay in. The Dragon is initially terrified of the ghosts, but then he realized that he knew who the ghosts were when they were still alive, and then the ghosts left the castle for some reason.