In 2001, Tribune reporter and River North resident Marja Mills traveled to Alabama in search of the notoriously private Harper Lee, who wrote the classic 1960 novel To Kill a Mockingbird. Lee refused to be interviewed. But their meeting led, improbably, to a years-long friendship between Mills, Lee, and Lee’s eldest sister, Alice, a centenarian lawyer who’s been called “Atticus Finch in a skirt.” Welcomed into the sisters’ small-town world, Mills ended up living nearby and started taking notes for a book.

Her memoir of that time, The Mockingbird Next Door: Life with Harper Lee (Penguin Press, $30), out July 15, provides some revealing anecdotes, such as when Mills watches the film Capote with Lee, who calls it “historical fiction.” Relayed in unfailingly wide-eyed prose, these vignettes struggle to cohere to form a satisfying narrative. But Mills succeeds in making a literary enigma a bit less of one.