Set in the twilight years of southern aristocracy, The Percys of Mississippi is a biography of a family in whose bloodline ran both a strong commitment to public service and an equally strong but more private dedication to literature. Following four generations of Percy family history, Lewis Baker chronicles the lives and public careers of Colonel William Alexander Percy, a planter and lawyer; his son LeRoy, a lawyer and United States Senator; LeRoy's son Will, a poet and lawyer; and Will's nephew and adopted son, the novelist Walker Percy.

Known as the ""gray eagle of the delta"" for his piercing eyes and silver hair, Colonel Percy served as a Confederate officer in both the eastern and western campaigns of the Civil War. He returned home to practice law and manage the family's property, but he was soon drawn into the arena of state politics, where he fought vigorously to strengthen the Mississippi River levee system and to protect his district from the perils of Reconstruction. With Colonel Percy's death in 1888, LeRoy Percy inherited his father's law practice and his mantle of leadership in the community. LeRoy used his power as a United States Senator to continue his father's long quest for an adequate levee system; struggled to loosen the Ku Klux Klan's grip of fear on the delta; and campaigned tirelessly to discredit the divisive creed of the state's rising demagogue politicians.

In the election of 1911, LeRoy Percy was defeated in his bid to be returned to the Senate, losing to the flamboyant demagogue James Kimble Vardaman, the ""White Chief."" It was a defeat echoed across the South throughout the dawning years of the twentieth century, as poorer whites rejected the moderate counsel of the planter class, their traditional leaders, and embraced the demagogues' fiery gospel of resentment. It was this troubling, altered South that LeRoy Percy bequeathed to his son William Alexander. Will Percy fought in World War I, taught for a time, and stood at his father's side throughout many of the battles to safeguard the delta from extremism. But Will's true calling was as a poet, and his lasting contribution to the delta would be in the form of a memorial to its past, his memoir Lanterns on the Levee.

""During my day,"" he wrote Will Percy not long before his death, "" I have witnessed the disintegration of that moral cohesion of the South which had given it its strength and its sons their singleness of purpose and simplicity."" It would be left to Walker Percy to fully confont htis modern, disintegrated South; to seek in such works as The Moviegoer, The Last Gentleman, and The Second Coming the place of the Percy family's values in a world that has little use for aristocrats.