In DeLuca’s GHOST BUSINESS (Berkley, 335 pp., paperback, $19), we find ourselves in Boneyard Key, the most haunted place in Florida. Tristan has come to set up a ghost tour, as he’s done across the country. He’s surprised to find Boneyard Key already has one — run by Sophie, who was raised here by her great-aunt — but he’s not deterred by a little competition. He has better marketing, better showmanship and better financing.