What was the name of the first Nancy Drew book?

Nancy Drew is a fictional character, a sleuth in an American mystery series created by publisher Edward Stratemeyer as the female counterpart to his Hardy Boys series. The longest-running series of books to feature Nancy Drew is the original Nancy Drew series, whose 175 volumes were published from 1930 to 2003. The first appearance of Nancy Drew was in the book "The Secret of the Old Clock" in 1930.

The books are ghost written by a number of authors and published under the collective pseudonym Carolyn Keene. Over the decades, the character evolved in response to changes in US culture and tastes. The books were extensively revised and shortened, beginning in 1959, partly to lower the printing costs cost with arguable success.

In the revision process, the heroine's original character was changed to be less unruly and violent.

In the 1980s, an older and more professional Nancy emerged in a new series, "The Nancy Drew Files", that included romantic subplots for the sleuth. The character proves continuously popular worldwide: at least 80 million copies of the books have been sold, and the books have been translated into over 45 languages.