“She wasn’t messing around, and neither have I,” Patterson said. “We both get down to business and chop wood.”

In the press release announcing the book, Little, Brown seemed dizzy at the commercial prospect of a multimedia project targeting Patterson and Parton’s audiences: “This double release will be a No. 1 for the first time. Being a bestselling author and an entertainment icon who has sold well over 100 million albums worldwide has collaborated on a book and an album. “

Patterson has long relied on a number of contributors to accomplish his frenetic publication cycle. According to his publicist, he has written 322 books and sold around 425 million copies. He has worked with around 35 co-authors and currently has several best-seller books including “The Shadow,” which he wrote with Brian Sitts, and “The President’s Daughter,” a political thriller he and the former president Bill Clinton wrote. It is a sequel to her previous novel “The President Is Missing,” which has sold more than 3.2 million copies worldwide.

But working with a celebrity as popular as Parton could spark even more interest in the upcoming book. She is one of the few public figures with seemingly non-partisan appeal, hailed by some as the southern heroine of the working class and venerated by others for her support for LGBTQ rights and uncompromising kitsch. (Parton has created their own Dollywood theme park in the foothills of the Smoky Mountains, which includes a water park, dinner theater, roller coaster rides, and a replica of their two-bedroom children’s home.)

“People love her,” said Patterson, stating the obvious.

After their first casual meeting (“No agents, no lawyers,” Patterson said), Parton and Patterson spent the next six to eight months working out scenes and pacing chapters and notes. Parton called him JJ, short for Jimmy James, he said.

They kept the project a secret, despite Parton derailing that she was a fan in an interview with the New York Times late last year. When asked to name three writers she would invite to a dinner party, she named him along with Maya Angelou and Charles Dickens.

“First would be James Patterson,” she said. “Since we’re both in the entertainment industry, we could write it off as a business expense.”