Nancy Drew Mystery Stories #25: The Ghost of Blackwood Hall book by Carolyn Keene

When Mrs. Putney seeks Nancy's help in recovering her stolen jewelry, the search for the thieves takes the girl detective and her friends, Bess and George, to an abandoned mansion in the River Heights vicinity known as Blackwood Hall and to the colorful French Quarter of New Orleans. When the quest is hampered by the strange behavior of Mrs. Putney and two young women who are being victimized by so-called spirits, Nancy must fight these unseen perpetrators of a cruel hoax! The resourceful young sleuth wants to help, but is hindered. The ghostly spirits have warned these gullible victims to not to have anything to do with Nancy Drew!