What if an empire of Jewish warriors that really existed in the Middle Ages had never fallen—and was the only thing standing between Hitler and his conquest of Russia? Eastern Europe, August 1942. The Khazar kaganate, an isolated nation of Turkic warrior Jews, lies between the Pontus Euxinus (the Black Sea) and the Khazar Sea (the Caspian). It also happens to lie between a belligerent nation to the west that the Khazars call Germania—and a city the rest of the world calls Stalingrad. After years of Jewish refugees streaming across the border from Europa, fleeing the war, Germania launches its siege of Khazaria. Only Esther, the daughter of the nation’s chief policy adviser, sees the ominous implications of Germania's disregard for Jewish lives. Only she realizes that this isn’t just another war but an existential threat. After witnessing the enemy warplanes’ first foray into sovereign Khazar territory, Esther knows she must fight for her country. But as the elder daughter in a traditional home, her urgent question is how. Before daybreak one fateful morning, she embarks on a perilous journey across the open steppe. She seeks a fabled village of Kabbalists who may hold the key to her destiny: their rumored ability to change her into a man so that she may convince her entire nation to join in the fight for its very existence against an enemy like none Khazaria has ever faced before. The Book of Esther is a profound saga of war, technology, mysticism, power, and faith. This novel—simultaneously a steampunk Joan of Arc and a genre-bending tale of a counterfactual Jewish state by a writer who invents worlds “out of Calvino or Borges” (The New Yorker)—is a stunning achievement. Reminiscent of Michael Chabon’s The Yiddish Policemen’s Union and Philip Roth’s The Plot Against America, The Book of Esther reaffirms Barton’s place as one of her generation’s most gifted storytellers.