The Hidden Staircase (Nancy Drew Mystery Stories, #2)

After receiving a call from her good friend Helen Corning, Nancy Drew agrees to help solve a baffling mystery. Helen's Aunt Rosemary has been living with her mother at the old family mansion, and they have noticed many strange things - music, thumps, and creaking noises at night, and seen eerie shadows on the walls. Could the house be haunted?

Helen's great grandmother, Miss Flora, thinks the house has a ghost. Nancy doesn't believe in such things, but she's puzzled and very anxious about Miss Flora's frail health.