Why the iconic adventure writer Jon Krakauer is telling the story of rape in a college town

Author Jon Krakauer's newest book came out Tuesday, and it's a complete departure for an adventure writer known for books like "Into the Wild."

The new book looks at the culture of sexual assault in a Montana college town and how police handled rape cases there.

Krakauer started researching sexual assault after finding out someone close to him had been raped, he told NPR's Rachel Martin in a recent interview. This person, Krakauer learned, had been raped twice as a teenager - once by an acquaintance and once by a family friend.

"I was shocked by this," Krakauer told NPR. He said he began looking into acquaintance rapes and discovered multiple references to sexual assault in Missoula, Montana.

His newest book, "Missoula: Rape and the Justice System in a College Town," dives into the home of the University of Montana, a city that has seen 230 rape cases in four years. Despite these seemingly staggering statistics, Missoula is "a pretty typical town," the author told NPR.

"I don't mean to single out Missoula: Its rape rate is a little less than the national average," Krakauer said. "I think its problems with dealing with rape are pretty depressingly typical."

There are other statistics about Missoula that seem to echo campus sexual assaults around the US. According to Krakauer, all of the 230 assaults in his book involved acquaintance rapes and, in most cases, the alleged rapist never received any punishment.

One case made a particular impression on Krakauer. He tells NPR about Allison Huguet and Montana football player Beau Donaldson, two high school friends who grew up together before going their separate ways for college.

Krakauer describes what eventually happened between the two friends, three years after leaving high school:

When they were both juniors, I think in 2010, she was back in town. All their high school friends were getting together at a party at Beau Donaldson's house. She went. You know, they drank a lot. She decided - a friend there said, "Oh, you've been drinking too much to drive home, why don't you sleep on the couch?" She did. She woke up in the early morning hours to Beau Donaldson raping her from behind - her best friend. She was terrified. He weighs 230 pounds; he's a Division I football player. She weighs 130 pounds. She decided, you know, just instinctively to just freeze, to pretend she was sleeping. When he was finished, he just kind of threw a blanket over her, left the room. As soon as she was sure he had left the room, she grabbed her shoes and her phone and started running out of the house.

In an excerpt from "Missoula," Krakauer expands on what happened between Huguet and Donaldson. The former Montana football player confessed to the rape in January 2012, and a year later was sentenced to a 30-year-prison sentence, with 20 years suspended, according to the Missoulian.

"People in Missoula need to know that if you rape an acquaintance, it is a serious crime," Missoula County Attorney Fred Van Valkenburg said at trial.

The Montana football team seems to have a history of being accused of acquaintance rape. As Krakauer writes in "Missoula:"

In December 2010, four of Beau Donaldson's teammates on the UM football team allegedly gang-raped a female student when she was too drunk to resist, and because the football players claimed the sex was consensual, they were not charged with a crime. A year later, in December 2011, three Griz football players sexually assaulted two female students after allegedly drugging them. None of these assailants was prosecuted, either.

With the book's release, some Missoula residents fear Krakauer's investigation will draw unwarranted attention to their college town home, even as it helps drive discussion of sexual assault.

"It's great, because it's raising attention to the issue," one Missoula resident told The New York Times. "But Missoula is not the issue."