The letter-loving trio at Spence Mansion has something to grieve about—Ghastly's post office is about to close, which will cut off their connection to their fans. A new invention called VEXT-mail is threatening to replace not only letters, but books, hair dryers, and even garage door openers! Could the mysterious occupant of P.O. Box 5 and his seemingly sinister plan save the doomed post office? Will he strike down Ghastly’s beloved ghostwriter in the process? In this fourth