NEW YORK -- "To Kill a Mockingbird" will not be Harper Lee's only published book after all.

Publisher Harper announced Tuesday that "Go Set a Watchman," a novel the Pulitzer Prize-winning author completed in the 1950s and put aside, will be released July 14. Rediscovered last fall, "Go Set a Watchman" is essentially a sequel to "To Kill a Mockingbird," although it was finished earlier. The 304-page book will be Lee's second, and the first new work in more than 50 years.

"The existence of 'Go Set a Watchman' was unknown until recently, and its discovery is an extraordinary gift," Harper publisher Jonathan Burnham said in a statement.

"To Kill a Mockingbird" is among the most beloved novels in history, with worldwide sales topping 40 million copies.