The Secret of The Old Clock

The Secret of the Old Clock is the first volume in the Nancy Drew Mystery Stories series written under the pseudonym Carolyn Keene. It was first published in November 1930. Nancy Drew is an eighteen year-old high school graduate. Her father, Carson Drew, is a well-known criminal defense lawyer. The Drews reside in River Heights and employ a housekeeper, Hannah Gruen. In early editions, she is depicted as a mere servant; later in the series she becomes more of a family member.

As of 2001, it ranked 53rd on a list of the all-time best-selling hardcover children's books in English; according to Publishers Weekly, it had sold about 2.7 million copies.