The main character as this book begins is the Reverend Willie Maxwell: part-time preacher, full-time ladies’ man. Handsome and well-dressed, Maxwell cut a swell figure in the late 1960s around Alexander City, Alabama. But when several of Maxwell’s family members met untimely deaths, the grieving Reverend could barely see through his tears to claim the multiple life insurance policies he had taken out on each of them.

He managed to escape conviction for any involvement in the deaths, but suspicion lingered as the body count rose over the next few years (two wives, a neighbor, a brother, and a nephew). When Maxwell’s teenage step-daughter also died in an “accident” in 1977, her uncle, Robert Louis Burns, snapped—and put down the Reverend with a .45 in front of all the mourners at her funeral. Burns never denied what he did, so the question was whether he would be convicted of murder for doing what many saw as a service to the community.

Casey Cep tells the story of the ensuing trial, and it has all the hallmarks of the archetypal Southern legal drama: the un-airconditioned Alabama summer courthouse, the charming liberal lawyer, the racial undercurrents (although, in this particular case, both the victim and the alleged killer were black).

It was a legal spectacle that Harper Lee hoped to write. Aged fifty, fifteen years after her literary triumph with To Kill A Mockingbird, she had yet to publish a second book. She installed herself in Alexander City to cover the trial and set about interviewing everyone involved. Her celebrity (and family connections) meant doors opened for her that would have been closed to others.

Cep retraces Lee’s steps, as the book turns into her biography. Lee is an enigmatic figure: we know her as a child from the character of Scout Finch. But she guarded her adult life closely. Cep details her upbringing and college years, how she dropped out of law school and moved to New York to pursue writing. In late 1959, her career had yet to take off when her childhood friend, Truman Capote, asked her to accompany him to Kansas as he researched In Cold Blood. She served as his assistant, gleaning information from reluctant townsfolk and taking notes.

So when she decided to write her own true crime piece, she had a model to follow (or, more accurately, to avoid). Cep suggests that Lee had not been impressed with the liberties Capote took with the truth in his work (although she did not say so publicly). She wanted to be accurate with her own book, even paying the court reporter to type up the entire transcript of the trial for her. She bought death certificates, tracked insurance records, collected all the newspaper clippings about the case.

Over the following decade, Lee claimed to various people to be making progress, to have written a draft, even to have sent it to the publisher. But the book never appeared. By then, Lee had spent decades writing and not-writing, and avoiding publicity. She always had plans for other novels, and her publishers were eager to see another bestseller. But somehow she just couldn’t do it.

The success of Mockingbird had overwhelmed her, but it also gave her the financial comfort to never have to work again. Perhaps that was a curse as well as a blessing: she wrote urgently when she was having to find time after her job as an airline agent, and finished Mockingbird at a sprint when some friends advanced her enough cash to stop working for a while. But she had written a book that wouldn’t just sell well, it sold (and sells) a million copies a year. Her agents even had to apologize for the volume of checks they were sending her. Maybe without the wolf at the door, she couldn’t find the creative spark.

Others have attributed her lack of productivity to alcoholism, pathological perfectionism, and depression—all of which Cep explores. We don’t know how much she wrote and discarded. So Cep has written here, in part, the book Lee could have written. We will never know if Lee would have created a true-crime classic, or turned the Reverend Maxwell’s story into a novel (a tantalizing idea it seems she also explored).

As with many authors of sparse catalogues, fans held out hope that more books by Lee would materialize—that the perfectionist author had in fact amassed a trove of manuscripts waiting to be released. But the publication of Go Set a Watchman, when she was near-blind and in a nursing home, raised eyebrows. After all, if she had wanted it published, surely she would have done so decades earlier? Her publisher had rejected it in the 1950s and steered her towards writing the story that became Mockingbird. Some saw its emergence as the work of over-eager lawyers or agents exploiting the elderly Lee’s legacy.

Similarly, though, if her executors had wanted to cash-in since Lee’s death, they would have dusted off any draft they could find and shipped it to HarperCollins. That they have not suggests there is nothing more to be found. So the mystery of the missing manuscript is the other “true crime” case for Cep to pursue.

Cep writes atmospheric prose, and laces together the two halves: the Maxwell case and Lee’s attempts to write about it. The book still meanders like a country stream, with detours into the history of life insurance, the origins of voodoo, the family trees of various players, and more. In fact, Harper Lee doesn’t really appear until halfway through. But the stream carries the reader forward, and this book is a creative gem.