Here's a snippet from the end of The Old, Dead Nuisance (and yes, it's a big spoiler).
For context, during the middle of the story Paul develops a relationship with the main ghost in the house, Josiah, who gives him hints about a fortune hidden right under everyone's noses.
Too late, Paul realises the fortune is a priceless Chinese Shang-dynasty vase—which has been destroyed in a tantrum by one of the fake psychics on the haunted house show.
When you read this snippet, compare Paul here to Paul at the beginning. How has he changed?