The Ghost of Sir Herbert Dungeonstone (Dragon Slayers' Academy #12)

What are those strange noises coming from the dungeon at DSA? Wiglaf and his stalwart cohorts Angus and Erica decide to investigate and inadvertently free the long-imprisoned ghost of the school founder-Sir Herbert Dungeonstone. Overjoyed to be on the loose again, Sir Herbert wreaks havoc, threatening to spoil the greedy headmaster's plan to turn DSA coed.