Marja Mills will discuss "The Mockingbird Next Door" at 7 p.m., Thursday, June 18. Free. Carter Presidential Library and Museum Theater, 441 Freedom Parkway, Atlanta; 404-865-7100, www.jimmycarterlibrary.gov/events/

In 2005, when biographer Charles Shields requested an audience with Harper Lee, the reclusive author of “To Kill a Mockingbird” not only told him no, but “hell no.”

She also instructed her friends to give Shields the brush-off.

It was a typical response from Lee, who, for more than 40 years after the publication of her Pulitzer Prize-winning novel, fended off almost every entreaty from the press.

Almost.

In 2001 Marja Mills, who will appear at the Carter Center on Thursday, June 18, struck up a friendship when she profiled Lee for the Chicago Tribune. Three years later Mills moved to Monroeville, Ala., renting the house next door to Lee’s home, shared by her older sister Alice.

For 18 months Mills and the Lee sisters shared meals, took road trips, watched football games, sipped coffee and visited back and forth with the Lees’ extended circle of friends and relations.

While Shields was cooling his heels in the foyer, Mills was in the inner sanctum. Mills’ 2014 memoir, “The Mockingbird Next Door: Life With Harper Lee,” just released in paperback, tells the story of that remarkable access.

There are many things it doesn’t tell. It doesn’t dwell on the friction between Harper Lee and her hometown, which led her to boycott the town’s staging of a theatrical version of the novel; it also led Lee’s attorney to file suit against the town’s history center for selling unlicensed “Mockingbird”-themed coasters, plastic tumblers and seat cushions.

It doesn’t tell of the 2007 stroke that ended Lee’s independence and sent her to an assisted living facility in Monroeville. That stroke occurred two years after Mills returned to her Chicago high-rise.

And nowhere does Harper Lee suggest to Mills that she has the manuscript for an earlier book hidden in a “secure location.” Yet such a book, called “Go Set a Watchman,” was discovered by Lee’s attorney, Tonja Carter and will be published next month by HarperCollins in a first printing of 2 million copies.

The discovery was the literary bombshell of the year: a “lost” sequel to a landmark novel written by an author known for writing one book and one book only.

The new book follows “Mockingbird’s” protagonist, Scout, who returns as an adult to the fictional Maycomb — a thinly-disguised Monroeville.

A meticulously-reported story in the Washington Post (with help from Shields) suggests that “Watchman” is not a first novel but simply the first draft of “Mockingbird.”

Others have questioned whether Lee, now debilitated by the stroke, actually approves of the book being released. Carter has vigorously affirmed that Lee was excited by the discovery. Carter also traded barbs with Alice Lee about the veracity of Mills’ memoir, claiming that Harper Lee did not cooperate as portrayed. Alice Lee died last November at age 103.

Into this brier patch, Mills treads gently. About “Go Set A Watchman,” she says, carefully, that the “circumstances around this can’t help but color how I feel about this (book) coming out.”

But, she adds, “so many people have told me that they savor the idea of being able to read more about Scout — to read the thoughts of an adult Scout returning to Monroeville.”

She said she doesn’t know if either Lee sister read her book, but never heard a response. Mills will speak about these and other issues at the Carter Center, though she is reticent on some questions.

Would Harper Lee, who Mills last saw in 2010, approve of her “forgotten” manuscript appearing as a new book? Mills would prefer not to guess.

“I think people will read this with a generous eye, knowing that this was an early effort.”

Mills is emphatic about one point: Alice Lee and Harper Lee (who is known in Monroeville by her first name, Nelle), both generously let Mills into their lives, at a moment that stands out as the end of an era.

Her memoir “ends up being a chronicle of the last chapter of life as they had known it all those years,” she said. “For so long they had certain routines and rhythms of life. And they invited me along for that.”