Local historians take readers beyond the celebrated charm of Mark Twain's boyhood home to its unexplainable and disturbing dark side.   After living in Rockcliffe Mansion, where the haunted hallways were a rite of passage for countless Hannibalian youth, Ken and Lisa Marks learned firsthand that Hannibal, Missouri, is indeed haunted. Hannibal's own Mark Twain held a lifelong fascination with paranormal activity after experiencing an uncanny premonition of the death of his brother in 1858. Even skeptics will find it hard to resist the marvelously strange history of the limestone cave made famous in The Adventures of Tom Sawyer where the real-life, macabre Dr. McDowell experimented with his own daughter's corpse. Stories of the town's notorious red light district and Hannibal's larger-than-life lumber barons provide even more spine-tingling evidence of the haunting of America's Hometown.   Includes photos!