The Invisible Intruder (Nancy Drew, Bk. 46)

"Nancy Drew, forget the ghost hunt!" a male voice rasps on the telephone. Despite the mysterious warning, the pretty teen-age detective and a group of friends start out on a ghost-hunting expedition to investigate five places reputed to be haunted. Danger strikes at once when Nancy tries to overtake the canoe that paddles itself on Lake Sevanee. Thrills and chills mount as the ghost hunters pursue a phantom horse and ghost rider racing across the field that surrounds the Red Barn Guesthouse.