The late ''Catcher in the Rye'' author was a famous man of mystery, but an upcoming biography and documentary promise to uncover the secrets to his genius

No writer’s private life has inspired as much fascination as J.D. Salinger‘s. The Catcher in the Rye author spent years avoiding curious reporters and passionate fans, until his death in 2010. Along the way he became the archetypal 20th-century writer-recluse. Although Salinger thwarted attempts at telling his story during his lifetime, screenwriter and director Shane Salerno promises that his biography, Salinger (out Sept. 3, co-written with David Shields), released jointly with a documentary of the same name (in select theaters Sept. 6), will provide unprecedented access, based on almost a decade of research and exclusive interviews with more than 200 people. ”Salinger was such a deeply private man that it took years to secure the participation of the people involved,” Salerno tells EW via email. ”They all found it hard to share intimate photos, diaries, and letters, but once they realized how committed we were to telling the full story, people trusted us with their other stories, memories, photographs, documents, and materials related to Salinger.”

The never-before-seen photograph above is just a taste of the tantalizing material the book promises to include. Taken during the liberation of Paris in late August 1944 by his friend and fellow Army counter-intelligence officer Paul Fitzgerald, it catches Salinger at a seminal moment in his life, just after a great victory for the Allied forces — ”It’s extremely unusual to find a photo of Salinger smiling like this,” notes Salerno — and just before he met his idol Ernest Hemingway in a Paris hotel, setting off a legendary literary friendship. ”Among many other revelations, the film and book show the public the first-ever images of Salinger at war,” Salerno says. ”I always knew such photos existed, but it took me nine years to locate someone who not only had the photographs but was willing to allow me to use them in my film and book.”

The snapshot also captures a defining moment for Salinger as a writer. ”World War II would be the crucible of his life,” says Salerno. ”He entered the war as a Park Avenue rich kid and returned home in 1946 a shell-shocked soldier suffering from post-traumatic stress disorder.” Those experiences would haunt his life and inform iconic works like The Catcher in the Rye and Franny and Zooey, lending them his trademark, generation-defining angst. ”In the horrors of war, Salinger found his voice, his post-traumatic tone,” Salerno says. ”He never before had really written full-out about either love or squalor. From 1946 until he stopped publishing in 1965, he would write about nothing else.”