From John and Abigail Adams to the Kennedys to the Clintons, power couples have captivated the national stage. As Steve Inskeep portrays in his absorbing “Imperfect Union” there was no pair more glamorous than John Charles Frémont and Jessie Benton Frémont during the turbulent years leading up to the Civil War. Inskeep, the host of NPR’s “Morning Edition,” deftly traces how the marriage mirrored the era’s ferment.

John Frémont was raised largely in the coastal South, the illegitimate child of a French citizen and an already wedded aristocrat. Trained as a cartographer, he rose to fame by his knack for self-promotion, publicizing a series of Western expeditions in which he mapped sections of the Rocky Mountains and the Great Basin, even stumbling into the United States’ acquisition of California and claiming himself conqueror. In truth his judgment was scattershot and often self-sabotaging, his physical courage real but his vanity insatiable, an “intrepid amateur who found out how much he could get away with.”

He married well. The favorite daughter of Thomas Hart Benton, Missouri’s renowned senator, Jessie had grown up transcribing notes in her father’s meetings, well acquainted with presidents and congressional leaders. From her mother she’d inherited an abolitionist bent, influencing her husband. Among their contemporaries Jessie was considered the smarter and more decisive of the pair. Behind the scenes she worked tirelessly for her spouse while he was away for years at a time; tended to three children; swept in and out of federal offices and Washington soirees. When the newly formed Republican Party nominated John Frémont for president in 1856, Jessie brought her formidable skills to bear; his supporters came up with a slogan, “Give ’em Jessie!” a century before Harry Truman’s “Give ’em hell!”

Vibrant and propulsive, “Imperfect Union” is by far Inskeep’s strongest book, reminiscent of work by Doris Kearns Goodwin and Jon Meacham. Inskeep re-creates the darker currents beneath Manifest Destiny while rescuing John and Jessie from the margins of history, seeing them as precursors to the epic struggles ahead: “The Frémonts grew famous in a more democratic way. … They spread their story to an increasingly literate public, and linked their names not to one, but three great national movements — westward settlement, women’s rights, and opposition to slavery.”

The book tapers off after the death of the colorful Sen. Benton (who had grown estranged from his son-in-law) and the Civil War; by this point the Frémonts were withdrawing from public life and from each other. In 1890 John died in New York, a continent away from his wife, while Jessie lived on with their daughter in Los Angeles for another decade.

“Imperfect Union” is a pure delight to read, but beneath Inskeep’s stylish sentences lurk astute insights, illuminating the outsized role celebrity plays in our culture, the outward triumphs and quiet pain it inflicted on two lives that left an indelible, if neglected, mark on our politics.

Hamilton Cain is the author of “This Boy’s Faith: Notes From a Southern Baptist Upbringing” and a member of the National Book Critics Circle. He lives in Brooklyn.

Imperfect Union
By: Steve Inskeep.
Publisher: Penguin Press, 449 pages, $32.