It's the title one scout called the "secret book of Frankfurt" and its pedigree—acquired un-agented by an editor at Knopf from the author, who was writing it in prison—is among the things that have piqued the interest of festival-goers in Germany.

Cherry, by Nicholas Walker, is a fictionalized account of the author's exceptional life. An Iraq veteran who won multiple commendations for valor as a medic in the war, Walker came back home and floundered, suffering from an intense case of PTSD. What set him apart was the salve he found for his condition: robbing banks.

Walker landed in prison in 2012 and his case—he became one of Ohio's most prolific bank robbers by knocking over 10 branches in four months—and his unique case caught the eye of a reporter. In 2013 Buzzfeed profiled Walker in a story by Scott Johnson called "How a War Here Became a Serial Bank Robber."

Knopf's Tim O'Connell, who acquired Cherry, told PW he heard about the author through a friend at the indie label Fat Possum Records. Fat Possum's Matthew Johnson reached out to Walker after reading the Buzzfeed piece and began a correspondence with him. When interest in a possible movie about Walker's life started to surface, Johnson, according to O'Connell, encouraged Walker to try his hand at writing a novel based on his own life.

"As it turns out, Nico was steeped in Ernest Hemingway and Thomas McGuane and, even more incredibly, was cut from much the same cloth," O'Connell said. "Nico found a typewriter and he began hammering out passages that would eventually grow into Cherry. Right away, I saw the electricity—a voice so fresh and raw."

After seeing pages from the novel, O'Connell went with Johnson to meet Walker in prison. From there, a deal was hammered out. As O'Connell put it: "I visited Nico with Matthew at the federal correctional facility where he is being held in Ashland, Ken. We sat there all morning, ate chips, and discussed the word 'ajar' for over an hour. That’s how it began. I knew I had a winner."