Oscar voters recently received their copies of The Way Back, a World War II epic scheduled to hit American screens on January 21. Meanwhile, controversy swirls around the story that inspired the movie. And Vermont author Linda Willis has a central role in it.

The Way Back boasts big names: stars Colin Farrell and Ed Harris; director Peter (The Truman Show) Weir. Like many award winners, it’s based on an uplifting book with “true story” in the title: The Long Walk: The True Story of a Trek to Freedom. First published in 1956, the book recounts the imprisonment of young Pole Slavomir Rawicz in a Siberian gulag, his daring escape with a few companions and their 4000-mile trek to safety in India.

Did it really happen? For decades, readers thought so. Yet, in a recent BBC interview, Weir calls the film “essentially fiction.”

Willis, a freelance writer who lives outside Middlebury, knows why. She was the first researcher to uncover proof that Rawicz — who died in 2004 — didn’t take the famous “long walk” himself. She was also the first to interview Witold Glinski, the man who very possibly did. Her book Looking for Mr. Smith: A Quest for the Truth Behind The Long Walk, the Greatest Survial Story Ever Told, published last October, presents the results of her decade-long research odyssey.

Willis calls herself “just a common ordinary person” who “got a bee in [her] bonnet” when she first read The Long Walk in 1999. Fascinated by the story, which covered some of the same terrain she had during three decades abroad, Willis wanted to corroborate Rawicz’s account. Strangely enough, no one ever had.

Ghostwritten by a British journalist, The Long Walk has sold more than 500,000 copies. Film rights were first optioned in 1956, and the book continues to be reprinted with the words “true story” on its cover. Yet, though Rawicz claimed three other escapees survived the trek, none ever stepped forward. Particularly mysterious was the character of “Mr. Smith,” described by Rawicz as an intrepid American who spoke perfect Russian.

So Willis went looking for Smith — and other witnesses and survivors. Her extensive research, conducted mainly through Internet searches, mailed requests and phone interviews, was a “hobby,” not a full-time occupation, she says.

That “hobby” put Willis in a select company of people around the world determined to discover the truth behind Rawicz’s gripping narrative. In a December 2010 blog post, Hugh Levinson, a BBC reporter who made a radio documentary on The Long Walk, calls Willis his “comrade in madness.” “Was it her incredible energy and resourcefulness that led her to write to hundreds of people, email many more and dig around in dusty archives across the globe over the course of 10 years?” he asks. “Or was she as bonkers as I was?”

Willis may not have been “bonkers,” but she was determined — and patient. Some of the information she sought was buried in old-school archives — such as the Polish Institute in London, which until recently was “floor-to-ceiling shoe boxes,” she says in a phone interview. Other documents became accessible only after the fall of the Soviet Union, and Willis worked with volunteers struggling to catalog them.

Over the decade of research, there were “times when it petered out,” she says. “A couple of months would go by, and all of a sudden a letter would arrive.”

But there was at least one Hollywood-worthy “break” in the case. In 2003, Willis got a call from an Englishman who had seen an ad she placed in a local newspaper. His father, he told her, was a survivor of the real “long walk” who had kept quiet for more than a half-century. Willis eventually interviewed this man, octagenarian Witold Glinski, and found his story persuasive. So did Levinson.

Meanwhile, Willis discovered evidence that Rawicz was somewhere else when the “long walk” occurred. Glinski speculates that the other refugee heard and appropriated his escape story.

But the mystery is far from solved. On January 4, the website ExplorersWeb published an interview with an 83-year-old who claims to have evidence that Glinski fabricated his “long walk” story, too. Arguments are currently flying online, with some commenters calling the tale a long-running hoax.

Willis is guarded about her reactions to these developments, but she isn’t ready to give up on the story. “I believe a walk took place,” she says. “The common touchstone to both versions was the presence of Mr. Smith. Both versions started out at a point in Siberia and ended in India. Whichever version you decide you want to believe, I believe that’s the way it went.”

Most importantly, though, she hopes the publicity surrounding the movie will encourage more people to come forward with documentation — and furnish new material for future editions of Looking for Mr. Smith.

Whatever the truth about The Long Walk, Willis says her research taught her a valuable lesson: If you want to know about the past, ask people who were there. Repeatedly, she says, children and grandchildren warned her that their elderly relatives didn’t want to discuss the war years.

Yet her questions precipitated floods of memories. “These families would get back to me and say, ‘He hasn’t stopped talking about this!’” Willis says. “Some [elderly] people didn’t want to burden their families; others didn’t think they’d be interested. [Talk to] these people now when you can. You’re really going to regret it later, when they’re gone.”