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Taking place in Washington just after the Civil War, The Lincoln Conspiracy barrels from the railroad-station murder in its opening scene to its final, fatal fire, like one of the many locomotives that populate this mystery thriller by Tim O’Brien, the executive editor of the Huffington Post. The trains here are emblems of the power and money of America’s titled nobility, lending the book literary hints of Frank Norris’ 1901 railroad-baron novel The Octopus.

O’Brien’s pivots on D.C. police detective Temple McFadden, a Dublin-born orphan, who comes by papers that reveal a larger plot behind Abraham Lincoln’s recent assassination. McFadden whirls through the book like a human tornado, taking beatings, giving them, dispatching bad guys to the next life, and generally tearing around a precisely rendered 19th century Washington, D.C., from one violent escapade to the next. His wife, Fiona, is no slouch either, and at one point deploys her medical training to chloroform a pursuer, at another to poison her attackers.

Historical figures abound, some actively moving the plot forward, like Mary Todd Lincoln, Sojourner Truth (who declaims her famous speech, “Ain’t I a Woman”), and Dorothea Dix, who founded St. Elizabeth’s Hospital. Others, like the early feminist Elizabeth Cady Stanton, Frederick Douglass, Walt Whitman, Andrew Johnson, members of Lincoln’s cabinet, and Lincoln himself, hover in the background. But it is Washington itself, circa 1865, that grabs the limelight. To obliterate the Washington Channel’s stench, “he thought to pull a kerchief to his face. Off in the distance, the Washington Monument was all foundation, a tapering quarter-built slab…Here and there were stone warehouses along the water bisected by alleys dotted and stuffed with tiny two-room huts and cabins…” The neighborhoods are vividly depicted, as is the atmosphere of a metropolis, much of it long paved over, partly disappeared, partly morphed into the District of today. Most compelling are the images of the Irish immigrant village of Swampdoodle, which “clung to itself like an encampment: tough, dour and wary, with row upon row of small shacks that immigrant and itinerant railroad workers inhabited in packs.” Swampdoodle’s de facto chief is Nail, a counterfeiter with arms always blue from ink. In a book crammed with colorful characters, Nail, with his club and ferocious wolfhound, is the most Runyonesque.

Conjuring up the lingering miasma of a war just past, O’Brien intertwines plots and counterplots, while the mystery holds to the end, as detective McFadden, his feisty wife, and their friend Augustus, an African-American intellectual, pursue the president’s killers. That chase allows O’Brien to delineate a society of extreme wealth and poverty and ferocious racism, reeling from the first industrial-scale war in history and polluted throughout by political corruption and cronyism. And that hunt leads the heroic trio to the posh aeries of the railroad barons, whose displays of wealth, arrogance, and shameless buying of democracy all seem familiar—rather like our own financial oligarchs, except back then they actually built something.