The news, when it came, was short and sweet. Standing on a Florida golf course last week, Gilbert King looked at his phone and saw a two-word text message from an old friend: “Dude. Pulitzer.”

Mr. King, much to his surprise, had just been declared the winner in the general nonfiction category for “Devil in the Grove: Thurgood Marshall, the Groveland Boys and the Dawn of a New America.” The book, about four black men falsely accused of raping Norma Lee Padgett, a 17-year-old white woman in Groveland, Fla., in 1949, unearthed a largely forgotten chapter in the long history of racial injustice in the United States, and explored, in painstaking detail, the tactics used by Thurgood Marshall, the future Supreme Court justice, to chip away at the foundations of Jim Crow law.

Though Mr. King did not know it, his publisher, Harper Collins, had nominated the book, which beat out Katherine Boo’s lavishly praised “Behind the Beautiful Forevers: Life, Death and Hope in a Mumbai Undercity,” winner of the National Book Award in the same category in November. The other finalist was David George Haskell’s “The Forest Unseen: A Year’s Watch in Nature,” a sharp-focus examination of a square meter of old-growth forest in Tennessee.

“I’m sure people who write the big, critically acclaimed books know if they’re in the running,” Mr. King said during an interview in his small walk-up apartment on the Upper East Side, a few blocks from Gracie Mansion. “But I’d just gotten a notice from my publisher that the book had been remaindered.”