The Hidden Staircase is the second volume in the Nancy Drew Mystery Stories series written under the pseudonym Carolyn Keene, published in 1930 and revised in 1959. The original text was written by Mildred Wirt Benson, and she has said that it is her personal favorite of the Nancy Drew Books she wrote.

The Nancy Drew Mystery Stories is the long-running "main" series of the Nancy Drew franchise, which was published under the pseudonym Carolyn Keene. There are 175 novels — plus 34 revised stories — that were published between 1930 and 2003 under the banner; Grosset & Dunlap published the first 56, and 34 revised stories, while Simon & Schuster published the series beginning with volume 57.