"I hope you know what I'm talking about when I say every once in a while, not very often, I know exactly what I'm supposed to do with my life, even if I can't explain why. The trick is to tune in for it, like scanning the radio for a favorite song."

Jordan Scott was raised in the small fictional town of Mesadale, Utah, an isolated community formed in 1890 after the Mormon church officially renounced polygamy (or "plural marriage"). Believing themselves the spiritual heirs to a tradition in which polygamy is not just a right but a mandate, the founders of Mesadale built a town dedicated to the principles of plural marriage. It's ruled by a man known as the Prophet, whose divine authority has been passed down through generation to generation, and whose leadership goes unquestioned. Marrying multiple women is essentially required—there is, in fact, considerable pressure to amass wives—and though the community's spiritual beliefs are fundamentalist, guns and drugs abound. As do, of course, rape and sexual assault, though they are often justified as a husband's marital right.

Jordan is a so-called "lost boy," kicked out of Mesadale at age 14 when he was caught holding a girl's hand. (The real reason, it is explained, is that in order for a society based on plural marriage to function properly, there must be significantly more women than men—thus old men take any opportunity to expel the young ones.)

As David Ebershoff's sprawling new novel opens, Jordan has just turned 20, and he's spent the six years since his expulsion coming to terms with his homosexuality and deprogramming himself from years of brainwashing. (Case in point: As a child he was told that Europe had "been destroyed in a battle of good and evil"—imagine his surprise at meeting his first Frenchman.) While surfing the internet at a Pasadena library, Jordan runs across a news story about his mother: She's been arrested, and has been accused of killing Jordan's father. It's then that Jordan has his radio tune-in moment. "I'm going to Utah," he announces. And so he does, back to the town he swore he'd left behind, to uncover the truth of his father's murder, make some sort of peace with his past, and pick up a hot gay lover along the way.

Were The 19th Wife simply a polygamist murder mystery featuring a cute gay detective and his cute pet dog, it'd be easy enough to recommend as a fun, quirky read, a salacious twist on the The Cat Who... mystery franchise. But Ebershoff intersperses Jordan's narrative with another storyline—that of Ann Eliza Young, Brigham Young's "19th wife," who famously divorced him, went on to become an anti-polygamy crusader, and remains a divisive figure in the Mormon church today. Ebershoff recreates chapters from Ann Eliza's actual memoir (called Wife No. 19), as well as sermons, newspaper articles, and academic essays—so while The 19th Wife is a work of fiction, it derives its shape and its themes from history. (For example, Mesadale is a fictional place, but actual towns like it are not without real-world precedent.)

In following Ann Eliza's life, Ebershoff traces the history of Mormonism, from the persecution Mormons faced in their early days to their relocation to Utah to their initial rejection of (and finally their embrace of) plural marriage. The story told here is an impressively nuanced one: Polygamy is not merely a clever way for men to rationalize sleeping around (though it is that), and the incredible strain it can place on men as well as women is well demonstrated. The book's best argument against polygamy comes not from Ann Eliza as she preaches and proselytizes against her ex-husband, but from Jordan, a skeptic who still loves his polygamist mom. He's an open-minded kid who nonetheless balks at the conditions in which he spent his childhood:

"I know some gay people think polygamy and gay marriage are part of the same stay-out-of-my-bedroom political argument, and I'm generally a live-and-let-live kind of guy, but it's all different when there are kids, and sure, anyone should have the right to sleep with whoever, and marry whoever—this is America, after all—but you can't do whatever you want when you've got kids."

This is historical fiction of the best sort, following the track of history closely enough to retain a compelling ring of authenticity, yet exploiting the flexibility of fiction in order to bring to life the fascinating, complex figures with whom the past is populated.