Hidden Staircase
Author: first_name: Mildred A. Wirt
last_name: Benson
Language: English
Year: 1930

In the second book of the series, Nancy Drew comes to the aid of elderly sisters Rosemary and Floretta Turnbull  to uncover the cause of strange hauntings in their old country mansion.  In the process, Nancy discovers a hidden staircase which leads her to the heart of the mystery.  Will Nancy's midnight adventure reveal the secret of the hidden staircase?  

The Hidden Staircase was written by Mildred Wirt Benson writing under the pseudonym Carolyn Keene. - Summary by Louise Jaeschke