There were moments when John McCain had no idea if his friend even knew he was there. For eight long years, at least once a month, McCain would drive to the veterans' hospital in Washington, D.C., to sit for hours at the bedside of his political mentor, Morris Udall. The legendary liberal Democrat had been first admitted in 1990 suffering from the effects of Parkinson's. By the end, the debilitating disease had taken away Udall's ability to speak and to recognize visitors. But McCain still went, bringing newspaper clippings about subjects that Udall loved most, like the environment and Native...