Late country singer Johnny Cash's first marriage has inspired a new book, which promises to expose the secrets of his tumultuous union with Vivian Liberto Distin. The novel is based on love letters exchanged before the couple married, while he was overseas with the US Air Force. Cash met Distin in Texas in 1950, three weeks before the Air Force sent him to Germany. They were married from 1954 and 1966 and had four daughters. Ann Sharpsteen, who co-writes I WALK THE LINE, says, "The letters really reveal the real man, unclouded by drugs. "Letters were his dreams, fears, a variety of subjects, fidelity, alcohol, faith. It's like reading someone's diary." Distin died in May 2005 following surgery to treat lung cancer.