Book excerpt: When Johnny Cash died in September 2003, the world mourned the loss of the greatest country music star of all time. I Walked the Line is the life story of Vivian Cash, Johnny's first wife and the mother of his four daughters. It is a tale of long-kept secrets, lies revealed, betrayal and, at last, the truth. Johnny and Vivian were married for nearly fourteen years. These years spanned Johnny's military service in Germany, his earliest musical inclinations, their struggling newlywed years, Johnny's first record deal with Sun Records (alongside Elvis Presley), his astounding rise to stardom, and his well-known battles with pills and the law. Vivian decided that, near the end of her life and with backing from Johnny, she should tell the whole story, even the parts at odds with the iconic Cash family image such as Johnny's drug problems; Vivian's confrontation with June Carter about her affair with Johnny and, most sensationally, the Cash family secret of June's lifelong addiction to drugs and the events leading up to her death. Also revealed are unpublished love letters between the couple, family photographs and artefacts. I Walked the Line is a powerful memoir of joy and happiness, injustice and triumph and is an essential read for all Cash fans.