Thick with mysteries dense as Southern summer air, Casey Cep’s Furious Hours: Murder, Fraud, and the Last Trial of Harper Lee leaves it to readers to determine the true crime within

“I’ve been surprised by the number of people who said they did stay up all night with the book, and it’s not for the section I would have thought,” says Cep, a writer from the Eastern Shore of Maryland whose work has appeared in the New Yorker,the New York Times,and the New Republic.“It was not to find out what happens to the reverend, it’s not to find out the verdict in the trial of this vigilante. It’s to find out what happened to Harper Lee.”

Cep’s New York Times–bestselling nonfiction debut is three books in one. It’s the story of the Rev. Willie Maxwell, a rural Alabama preacher accused of murdering five family members for nearly $100,000 of insurance money in the 1970s (about half a million dollars today). It’s also the story of Dixie Democrat Tom Radney, the charismatic white attorney who represented Maxwell—and, subsequently, Maxwell’s killer, Robert Burns. Finally, it’s the story of Nelle Harper Lee, author of To Kill a Mockingbird, who was nearly two decades into her tenure as a literary titan when she returned to her native state to report on Burns’ trial.

“Now, finally, she was ready to try again,” Cep writes in Furious Hours. “One of the state’s best trial lawyers was arguing one of the state’s strangest cases, and the state’s most famous author was there to write about it. She would spend a year in town investigating the case, and many more turning it into prose. The mystery in the courtroom that day was what would become of the man who shot the Reverend Willie Maxwell. But for decades after the verdict, the mystery was what became of Harper Lee’s book.”

Lee never completed the book she planned to call The Reverend,stymied by “the shortage of facts, the lack of an ideal protagonist, her unfamiliarity with the lives of African Americans, a certain uncomfortable moral muddiness concerning black criminality in a criminally racist society, and a related discomfort with her own deep delight in the self-serving mythologies of the southern gentry,” Cep writes.

“I would never have anticipated the kind of fascination people would have with writer’s block,” says Cep, who logged countless hours of reporting and writing where Lee left off, “but [readers] are rooting for her and want to know how it all turns out.”

Furious Hours Kirkus calls Furious Hours an “effortlessly immersive…impressively researched narrative”—one that’s part literary biography, part geopolitical history, and part true crime.

“There are a series of murders and suspicious deaths at the heart of this book,” Cep says, “and I tried very hard to treat them sensitively, mindful that those people all have living relatives and descendants, and there is real pain and anguish. [But] I think the more interesting crime is the financial one. That, to me, is where it got interesting for Harper Lee, too. We think of money as a motive, but money is also a means.

“If you look back at the history of politics in this period,” she says, “the disenfranchisement of black voters, the misapplication of so many federal protections that were attempting to strike at the heart of Jim Crow that failed over and over again because the law was abused, that’s obviously a different kind of crime but a crime all the same.”

Megan Labrise is the editor at large and hosts the Fully Booked podcast.