Jan-Andrew Henderson (1962-) is a Scottish author of 33 children's, teen, YA, and adult fiction and non-fiction books. Though mainly a thriller writer, he is best known for helping to popularize Edinburgh's Underground City and its supernatural lore, especially the Mackenzie Poltergeist in Greyfriars Graveyard.Henderson was instrumental in bringing Edinburgh's forgotten Underground City to public attention, with the first-ever book on the subject The Town Below the Ground, followed by Secret City. His book on supernatural Edinburgh the helped cement the town's haunted reputation while the Ghost That Haunted Itself and Father Figure catapulted the unknown Mackenzie Poltergeist to fame, as one of the world's best-documented supernatural cases. He is also the founder of City of the Dead a gh