A secret posthumous memoir by Dolly Parton has reportedly sold for $US13 million ($18.5 million) following a bidding war between publishers.

According to Page Six, Grand Central Publishing secured the book after competing publishers were initially told the offer had reached $US12 million.

The memoir was reportedly sold by literary agency Folio, which also represented Parton’s 2023 book, Songteller: My Life in Lyrics.

One source said publishers were surprised by the asking price, saying: “no one believed them, so they all stopped bidding [and] Folio went back to editors.”

“They were all like, ‘WTF? You have $12 million, and we aren’t beating that,’” another source said.

However, Grand Central later improved its offer and secured the book, with multiple sources telling Page Six the final deal reached $US13 million.

Another source said the deal involved a lower upfront payment but a larger share of royalties, with the publisher and estate reportedly agreeing to a 50/50 split.

The deal is among the biggest celebrity book agreements, including Britney Spears who secured a reported $US15 million for her memoir in 2022 and Bruce Springsteen who received more than $US10 million for his book in 2016.

It is not known when Parton wrote the memoir or what it will reveal about her life and whether it will cover details about her private health battle.

Parton published several books during her career, including her 1994 autobiography, Dolly: My Life and Other Unfinished Business, and Songteller. She also worked on children’s books, a novel with James Patterson and a cookbook with one of her sisters.

Representatives for Grand Central Publishing and Parton did not respond to requests for comment, according to Page Six.

Her longtime manager, Danny Nozell, previously said the singer had spent years preparing projects for the future.

“Dolly worked up until the day she died. She loved seeing her dreams come to life, and loved knowing her work brought people joy. Ever the planner, Dolly worked with the team that she hand-picked, for the past several years to build a project roadmap that will guide us for decades to come.”

He added that fans could expect more releases through her official channels.

“Many projects were in various stages of development, and we want to be transparent with her fans about this fact. If you see unreleased music, products, books, experiences, and campaigns launched through official Dolly Parton channels, you can have confidence in knowing that she placed her personal stamp on it.”

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