Harper Lee
Former US President George W Bush (R) before awarding the Presidential Medal of Freedom to American novelist Harper Lee (L), in this file photo taken on 5 November, 2007.Reuters

Around five decades after "To Kill a Mockingbird" was published, author Harper Lee is prepping to get its sequel out.

The 88-year-old US author had set aside this unpublished novel, titled "Go Set a Watchman", to concentrate on writing "To Kill a Mockingbird". This means, it wasn't planned to be a sequel at all; in fact, it was the one written first. The manuscript – which was discovered last autumn – was attached to an original typescript of Lee's award-winning novel.

"I hadn't realised it [the original book] had survived, so was surprised and delighted when my dear friend and lawyer Tonja Carter discovered it," Lee said, according to Sydney Morning Herald.

Publisher Harper Collins announced on Tuesday that the 304-page book will hit the shelves on 14 July. The story revolves around the same characters – Scout and Atticus Finch – but is set 20 years after the time frame exhibited in her previous and only published novel till date, apart from a number of biographies that were aimed at focussing on her life and work.

The adult Scout returns from New York to visit her father (lawyer Atticus Finch) at her childhood home in Maycomb, Alabama, during the peak of the 1950s Civil Rights movement.

"She is forced to grapple with issues both personal and political as she tries to understand her father's attitude toward society, and her own feelings about the place where she was born and spent her childhood," the publisher's announced. 

Lee wrote the novel in the mid-1950s, but after being advised by her editor, put it aside. "I was a first-time writer, so I did as I was told," Lee said, BBC reports. "After much thought and hesitation, I shared it with a handful of people I trust and was pleased to hear that they considered it worthy of publication."

"I thought it a pretty decent effort." The author further said. "I am humbled and amazed that this will now be published after all these years."

Lee won the Pulitzer Prize for her previous novel, which sold well and was also turned into a classic Hollywood flick just two years after it came out.

Harper Collins' Jonathan Burnham called "Go Set a Watchman" "a remarkable literary event" whose "discovery is an extraordinary gift to the many readers and fans of To Kill a Mockingbird".