Mormon missionaries. We've all seen them: well-scrubbed young men in suits and ties, biking down our streets two by two, knocking on doors with a message of faith and repentance. Some of us have even invited them into our homes and listened to their testimony of an angel who brought new scripture to a simple 19th-century farm boy named Joseph Smith. There are 90,000 of these missionaries posted around the globe, forsaking home and worldly pursuits for two years apiece. But as familiar a sight as they are, how many of us know what their lives are really like—or far they'll go to preserve and defend their faith?

William Shunn knows, having served a Mormon mission in Canada, and he's not afraid to tell in this witty, ribald, and thought-provoking memoir. He takes us back to his youth in Reagan-era Utah, where the pressures of family and community combine to push him and his friends out of the nest at the tender age of nineteen—and into a world where movies, music, and girls are off-limits, seventy-hour weeks are the norm, and everyone's first name is "Elder."

With refreshing candor, Shunn recounts the rites of passage every new missionary undergoes. He writes frankly of his homesickness and doubt, and of the startling hypocrisies among his fellow laborers that send him AWOL in the days after Christmas. And he chronicles the ill-fated rehabilitation that leads directly to his arrest in Calgary on charges of terrorism.

Along the way, he weaves his own story with that of Joseph Smith, Mormonism's charismatic founder, a martyr whose remarkable accomplishments are evident in the thriving religion he left as his legacy. Shunn draws insightful parallels between his arrest and imprisonment and Smith's many brushes with the law, and the two narratives come thrillingly together as both men face the judgment of their peers, one in a Canadian court of law, and the other at the hands of a frontier mob. And though Smith and his church do not emerge unscathed, the most rigorous scrutiny of all is reserved for the author himself.

The Accidental Terrorist is the first book to pierce—not to mention deflate—the veil of mystery shrouding those deceptively earnest preachers of the Mormon faith. With an unsparing eye William Shunn paints not an idealized portrait of constant disciples, but a tumultuous canvas filled with flesh-and-blood boys wrestling the greatest questions of existence. A tough but good-humored dissection of the making of religious fanatics, and a tour-de-force of self-examination, The Accidental Terrorist illustrates the high jinks and hazards that result when curious young minds submit to the straitjacket of blind faith. It's a journey unlike any you've ever read.

This long-awaited memoir from Hugo and Nebula Award–nominated author William Shunn, based on his popular podcast, appears in the fall of 2015 from Sinister Regard Publishers.