In America's 20th-century historical myth, author Lance Morrow says, John F. Kennedy is the Light Prince, Richard Nixon is the Dark Prince and Lyndon Johnson is the False Claimant who came in-between the shapeshifter'' who was part victim, part monster. This has its truth of course, as all myths do. But in ways we don't often consider, these three memorable, if not great, presidents had their similarities. They were of the same generation, shaped by Depression and World War. And they each made key personal choices in the year 1948 that ultimately led to both their triumphs and downfalls. Morrow, a veteran Time magazine writer who now teaches at Boston University, zeroes in on that year and those choices in The Best Year of Their Lives: Kennedy, Johnson and Nixon in 1948, his perceptive, provocative rumination on how the United States started down the path to what it is today. All three men were relatively young congressmen in 1948. Nixon and Kennedy were at the start of their political careers, but Johnson was in the middle of his, and he was deeply frustrated. His primary campaign to move up to the Senate revealed him to be a man willing to do anything to gain power. Nixon in 1948 maneuvered to national prominence by inserting himself into the epic showdown between Whittaker Chambers and Alger Hiss over Chambers' accusation that Hiss had been a Communist spy. At the expense of both men, Nixon emerged as the Young Crusader, headed for the stars. It was a deeply traumatic year for Kennedy, whose favorite sister, Kathleen, died in a plane crash. Family patriarch Joe Kennedy lied about the circumstances of her death. And Kennedy himself decided to lie about his near-fatal attack of Addison's disease the start of years of deceit about his health. In writing that is always thoughtful and sometimes gorgeous, Morrow shows that his protagonists opted for amorality at a time when the nation itself was struggling with its post-war self-image. Anne Bartlett is a journalist Washington, D.C.